JPS63151821A - Mount structure of gas flow rate measuring apparatus - Google Patents

Abstract

PURPOSE:To make an engine compact, by directly mounting an apparatus for measuring a gas flow rate to a box body. CONSTITUTION:One opening end part of either one of a gas flow rate measuring apparatus 100 and a box body 200 is inserted in the other opening end part to directly connect the apparatus 100 and the box body 200 to form a compact gas passage. Since a first protruding part formed to the grommet 60 engaged with the opening end part on the insert side has a diameter larger than the diameter of the inner periphery of the opening end part on the side to be inserted, said first protruding part is rubbed with the inner peripheral wall surface of the side end part to be inserted at the time of insertion to be plastically deformed in the direction opposite to the insert direction and the mounting backlash due to the vibration transmitted from the moving member peculiar to the apparatus 100 in the axial direction thereof is hard to generate. Since a second protruding part has a diameter almost the same as that of the inner periphery of the opening end part on the side to be inserted, the backlash of the apparatus 100 can be eliminated. Therefore, the apparatus 100 is strongly and compactly fixed to the box body 200 and excellent accuracy can be developed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a mounting structure for a gas flow rate measuring device that measures the flow rate of gas, such as air, flowing in a flow path pipe.

[Conventional technology]

2. Description of the Related Art Conventionally, vehicle engines have been equipped with an air flow measuring device for measuring the amount of air in order to supply the engine with an amount of fuel corresponding to the amount of air taken into the engine.

In recent years, various types of such measurement devices, such as vane type, hot wire type, and Karman vortex type, have been developed for use in vehicles, and some of them are actually used.

In the vane type air flow measuring device, as shown in Japanese Patent Publication No. 12865/1986, for example, a rectangular vane (dam plate) that is set to be able to rotate across the cross section of a rectangular flow path is used to measure air flow. It rotates in response to the pressure difference caused by the flow, and the air flow rate is measured from this rotation angle.

However, with the vane type air flow measuring device mentioned above,
As the air flow rate increases, the opening degree of the vane increases, and the vertical component of the pressure receiving surface of the vane to the air flow, which receives pressure from the air flow, decreases. Since the proportion transmitted to the vane side decreases, in the high air flow range, the change in the opening degree of the vane in response to a change in flow rate, that is, the change in the rotation angle of the vane, is extremely small.Therefore, measurement accuracy in high air flow conditions is reduced. The problem was that it wasn't enough.

Furthermore, in the configuration shown in the above publication, in order to suppress the vanes from vibrating due to the pulsation of the air flow and from changing excessively due to sudden changes in the air flow rate, A fan-shaped chamber is formed, and the vane is connected to a damping plate that revolves around this chamber, so that the air damping function of the chamber and the damping plate is applied to the vane. However, in order for this fan-shaped chamber to have a sufficient air damping function, its size (volume) cannot be made too small, and it is set so that it protrudes laterally with respect to the air passage. As a result, the device itself becomes large, and there are many regulations when installing it in a vehicle, that is, there is a problem that it is difficult to install it in a vehicle.

In view of these problems, the applicant has filed a patent application for patent application No. 60-259.
As in No. 136, a gas flow path through which the gas to be measured flows in the axial direction thereof, and a movement set in the gas flow path in a state where the gas to be measured can move linearly along the flow direction of the gas to be measured. a member; a flow path pipe having the gas flow path formed therein so that the cross-sectional area of the flow path increases along the flow direction of the gas to be measured at least within the movement range of the moving member; and the movement a shaft extending from the member along the flow direction of the gas to be measured; and fixedly set in the gas flow path with the flow path pipe, supporting the shaft in a movable state according to movement of the movable member. a bearing; a pressing member that applies a pressing force to the moving member in a direction opposite to the flow direction of the gas to be measured; a conversion means that converts the amount of displacement of the shaft into an electrical signal; one end is closed by the moving member; a first cylinder extending along the flow direction of the gas to be measured, the other end of which is closed and the other end of which is open, and the first cylinder is fixedly set in the gas flow path with the flow path pipe, and has one end closed and the other end open. , has filed an application for a gas flow rate measuring device comprising a second cylinder that fits into the first cylinder through a small gap.

A gas flow rate measuring device with such a configuration has a structure in which the moving member moves along the flow direction of the gas to be measured depending on the flow rate of the machine to be measured. Small vibrations in the flow direction, ie, the axial direction, occur constantly. Furthermore, vibrations caused by the vehicle running and vibrations from the engine itself are transmitted to this gas flow measurement device, so when installing this gas flow IT measurement device, it must be fixed firmly enough to eliminate these vibrations, and the connection of this gas flow measurement device must be made. A high degree of airtightness is required in the area.

[Problem that the invention seeks to solve]

By the way, in recent years there has been an extremely strong demand for more compact vehicle engines (not only reducing the size of each engine component itself, but also reducing the number of parts and integrating various parts). Generally, a gas flow rate measuring device is placed downstream from a box body such as an air cleaner or an air intake duct, but the conventional vane type device shown in Japanese Patent Publication No. 12865/1986 mentioned above has been used. Since the shape of the air flow measuring device is large and complicated, even if an attempt was made to attach the air flow measuring device directly to the box body in order to meet the demand for downsizing the engine, it would be extremely difficult to do so. Piping such as a rubber hose was required to connect the box and the air flow measuring device.

An object of the present invention is to make the engine more compact by directly attaching the gas flow measuring device such as the one disclosed in Japanese Patent Application No. 1982-259136 to the box body.

Therefore, the present invention provides a gas flow path through which the gas to be measured flows in the axial direction thereof, and a movement set in the gas flow path in a state where the gas to be measured can move linearly along the flow direction of the gas to be measured. a member; a flow path pipe having the gas flow path formed therein so that the cross-sectional area of the flow path increases along the flow direction of the gas to be measured at least within the movement range of the moving member; and the movement a shaft extending from the member along the flow direction of the gas to be measured; and fixedly set in the gas flow path with the flow path pipe, supporting the shaft in a movable state according to movement of the movable member. a bearing; a pressing member that applies a pressing force to the moving member in a direction opposite to the flow direction of the gas to be measured; a conversion means that converts the amount of displacement of the shaft into an electrical signal; one end is closed by the moving member; a first cylinder extending along the flow direction of the gas to be measured, the other end of which is closed and the other end of which is open, and the first cylinder is fixedly set in the gas flow path with the flow path pipe, and has one end closed and the other end open. , a second cylinder that fits into the first cylinder through a small gap, a gas inlet opening end of a gas flow rate measuring device, and a gas outlet of a box through which gas before measurement flows. In a mounting structure for a gas flow rate measuring device in which end portions are connected, the outer periphery of one of the gas inlet opening end of the gas flow rate measuring device and the gas outlet opening end of the box body is provided. , a grommet made of an elastic member is fitted therein, and the grommet has a first grommet having an outer circumference larger than the inner circumference of the other open end of the gas inlet opening end and the gas outlet opening end. a raised part and a second raised part whose outer periphery has a diameter that is approximately the same as the inner periphery of the other opening end; The open end portion into which the grommet is fitted is inserted into the other open end portion, and the first raised portion of the grommet is plastically deformed and comes into contact with the inner periphery of the other open end portion. This is a mounting structure for a gas flow rate measuring device.

[Effect]

With this configuration, by inserting the open end of either the gas flow rate measuring device and the box body into the open end of the other, the gas flow rate measuring device and the box body are directly connected to form a compact gas passage. Ru. Of the first and second raised parts formed on the grommet fitted to the open end on the insertion side, the first raised part has a larger diameter than the inner circumference of the opened end on the inserted side. During insertion, it is rubbed against the inner circumferential wall surface of the inserted end, plastically deformed in the opposite direction to the insertion direction, and in this state is crimped against the inner circumferential wall surface of the inserted side, improving airtightness. In addition, since the gas flow rate measuring device is firmly fixed especially along the axial direction, it is difficult to install the device due to vibration caused by the movement of the moving member in the axial direction, which is unique to this gas flow rate measuring device. Moreover, once it is inserted into the inserted end, it becomes difficult to come out.

On the other hand, since the second protuberance has approximately the same diameter as the inner circumference of the open end on the inserted side, vibrations caused by the vibration of the vehicle or the engine itself may cause the gas flow rate measurement device to move in directions other than the axial direction. Since it has a positioning function that prevents it from shifting, it eliminates rattling of the gas flow rate measuring device and maintains high measurement accuracy. Therefore, the gas flow rate measuring device is firmly and compactly fixed to the box and exhibits excellent accuracy.

〔Example〕

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

The measuring device shown in FIGS. 5 to 9 shows the configuration of an embodiment of an air flow rate measuring device for measuring the air flow rate taken into a vehicle, particularly an automobile engine. The flow pipe 1 constitutes a part of the intake pipe of an engine (not shown), and is composed of three housings la, lb, and lc'. The housings are circular in shape, and the housings la, lb, and lc are arranged linearly and on the same central axis. An air flow path 2 through which air flows in the axial direction is formed inside the flow path tube 1 constituted by the housings la, lb, and lc. In addition, each housing la, lb, lc is securely sealed at each joint 1d, le so that there is no ventilation with the outside, and each housing la, lb,
When lc is made of a resin material, sealing is performed by adhesion or welding. Further, the joint parts 1d and le are made thicker by raising the outer peripheral part of the housing, thereby firmly joining the housings together.

A moving member 3 made of a resin material is provided in the air flow path 2 and is configured to be able to move linearly along the air flow direction. It has a convex shape on the upstream side, and the convex surface forms a smooth curved surface centered on the central axis of the flow path pipe 1.

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

Further, the air inlet end IA on the upstream side of the housing 1a has a minimum air passage area at the most upstream position of the moving member 3, that is, between the outer edge 3a of the moving member 3 and the inner circumferential wall surface Lal of the housing 1a. A fully closed stopper 1a2 that regulates the fully closed position of the movable member 3, which becomes (bobo zero), is located on the central axis by three ribs 1a3 extending from the inner circumferential wall surface 1al of the housing 1a in the central axis direction of the rehousing la. When the movable member 3 is in the fully closed position, the movable member 3 is set on the central axis of the housing la (see Fig. 6). The apex comes into contact with the fully closed stopper 1a2. Note that each rib 1a3 has a streamlined cross-sectional shape so as not to disturb the air flow.

Further, a bypass passage 1a4 that bypasses the moving member 3 of the air flow path 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, a threaded portion 1a41 is formed on the inner peripheral wall surface of the bypass passage 1a4, and by screwing in or unscrewing the bypass screw 4, the bypass screw 4 moves back and forth within the bypass passage 1a4. Note that an O-ring 5 is provided between the bypass screw 4 and the inner circumferential wall surface of the bypass passage 1a4 to ensure sealing in 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 movable member 3 is configured to be housed in an outer cylinder 3b and an outer cylinder 3b having an outer diameter smaller than the diameter of the cylindrical outer edge part 3a extending downstream along the air flow direction. The inner cylinder 3C is integrally formed. The outer cylinder 3b and the inner cylinder 3C are both centered on the central axis of the housing la, and the outer cylinder 3b and the inner cylinder 3C are
A predetermined interval is set between the two. Also, outer cylinder 3
b and the inner cylinder 3c are both closed at their upstream ends by the moving member 3, and are open at their downstream ends.

Furthermore, a shaft 3d extending downstream in alignment with the central axis of the housing la is integrally connected and fixed to the moving member 3.

Next, the housing lb has four ribs lbl extending from the inner peripheral wall surface of the housing 1b in the direction of the central axis of the housing 1b.
(See FIG. 7), a cylindrical large diameter cylindrical portion 1b2 supported by this rib lbl, an intermediate cylindrical portion 1b3 provided to be housed within this large diameter cylindrical portion 1b2, and this intermediate cylindrical portion 1b3. A small diameter cylindrical portion 1b4 provided so as to be surrounded by is integrally formed. The above large diameter cylindrical part 1
b2, 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 equal to the outer cylindrical portion 3 of the moving member 3.
b is slightly larger than the outer diameter of the intermediate cylindrical portion 1b3.
The outer diameter of 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 outer diameter of the small diameter cylindrical portion 1b4 is smaller than the inner diameter of the inner cylinder 3c of the moving member 3. It is set small.

The small-diameter cylindrical portion 1b4 communicates in the axial direction, and the shaft 3d passes through the central axis thereof. This small diameter cylindrical portion 1b4 has two sets of bearing portions 6a made of ball bearings,
6b is held by a retainer 7 and fixed on its inner circumferential side, and the shaft 3d is moved in the central axis direction by a bearing 8 consisting of bearing parts 6a, 6b, retainer 7, small diameter cylindrical part 1b4, etc. freely supported. In addition, in this bearing 8, the bearings 6a and 6b are each set in series in the retainer 7, and both bearing parts 6a and 6b are urged in opposite directions by a spring 9 set between them. The bearing portion 6a is held in contact with the end of the retainer 8, and the bearing portion 6b is held in contact with a ring-shaped holder engaged with the retainer 7.

The large diameter cylindrical 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 cylindrical portion 1b2 with a predetermined appropriate clearance, that is, a minute gap. , the outer cylinder 3b is configured to move within the large diameter cylindrical portion 1b2 in accordance with the movement of the moving member 3 from the fully closed state to the fully open state. The downstream side of the large diameter cylindrical portion 1b2 is a cover I formed integrally with the housing 1c, which will be described later.
It is sealed from the air passage 2 by C1, and therefore the space formed by the large diameter cylindrical part 1b2 and the outer cylinder 3b communicates with the air passage 2 only through the clearance part between the large diameter cylindrical part 1b2 and the outer cylinder 3b. An air damper chamber 10 is configured to stabilize fluctuations in the moving member 3 due to pulsation of air flow or sudden changes in air flow rate.

Inside this air damper chamber 10, the moving member 3 is placed on the fully closed direction side,
That is, a coil spring 11 that presses in a direction opposite to the air flow direction is set, and one end of the spring 11 contacts 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 threaded part 1b41 is formed on the outer circumferential wall surface of the small diameter cylindrical part 1b4, and a slider 12 is engaged with this threaded part 1b41.By adjusting the position of this slider 12, the spring 11 is moved relative to the moving member 3. The pressing force is adjusted. In order to adjust the pressing force of the spring 11, slider 1
A plurality of annular holes 12a are formed at regular intervals on the downstream side of the cylindrical portion 2, and a large diameter cylindrical portion 1b2 and an intermediate cylindrical portion 1b3.
, a partition wall 1 formed at each downstream end of the small diameter cylindrical portion 1b4.
An arcuate window 1b51 communicating with the partition wall 1b5 is set in b5 corresponding to the hole 12a (see FIG. 7). Adjustment is performed by fitting a jig (not shown) into the hole 12a through the window 1b51, rotating the slider 12, and moving the slider 12 forward and backward along the threaded portion 1b41.

Note that an O-ring 13 for fixing the position of the slider 12 is set between the slider 12 and the intermediate cylindrical portion 1b3.

In addition, an intake air temperature sensor 14 is set in the lip Ibl, and is housed in a metal cap 14a that is integrally molded with a spherical tip protruding toward the upstream side when the housing 1b is molded. , lead wire 14b is connected.

Further, a connector 1b6 is molded in the housing 1b, and a plurality of conductive bottles 15 for signal extraction are molded together with a bottle holding member 15a through the inside of the rib lbl so that one end of the connector 1b6 protrudes into the connector 1b6. Fixed. The other end of the bottle 15 is connected to a lead wire 14b of the intake air temperature sensor 14, and is also connected to a sensor (potentiometer 18) that detects the amount of displacement of the moving member 4, which will be described later, and converts it into an electrical signal. Note that the bottle 15 is first molded and fixed in an L-shape to a pin holding member 15a made of resin, and the bottle 15 held by this pin holding member 15a is molded and fixed during molding of the housing lb etc. so as to pass through the inside of the rib lbl. .

In order to prevent the lead wire 15b of the intake temperature sensor 14 from playing within the rib lbl where the intake temperature sensor 14 is set, a lead wire holding member 14b1 made of rubber is attached to the rib lbl.
It is prepared accordingly.

Further, the lead wire 14b is guided by a groove 16 formed between an arcuate protuberance 1b7 and an annular protuberance 1b8 that were integrally formed on the downstream side of the partition wall 1b5 during molding of the housing 1b, and is guided by a groove 16 formed at one end of the bottle 15. It is connected to the. In addition,
A portion of the lead wire holding member 14bi is fitted into the raised portion 1b8, and is guided to the groove 16 portion by this lead wire holding member 14b1.

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

This 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 by using double-sided tape 18a between the potentiometer 18 and the holder 19.
are set and bonded to the potentiometer 18 and the holder 19, and the three protrusions 19a formed on the holder 19
and a hole 19b formed at a position facing this protrusion 19a.
Each protrusion 19a is held by a U-shaped plate spring 22 fitted into the plate spring 22, and the spring force of the plate spring 22
The potentiometer 18 is held in the horizontal direction by pressing the potentiometer 18 in the direction, and held in the vertical direction by the pushing back portion 22a of the leaf spring 22.

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

Further, at the end of the shaft 3d passing through the bearing 8, there is provided a slider 24 to which a brush 23 is fixed, which slides on the circuit pattern of the potentiometer 18 according to the displacement of the shaft 3d, that is, the movement of the moving member 3. (See Figure 8).

The end portion of the shaft 3d that protrudes downstream through the bearing 8 when the movable member 3 is fully closed is threaded and has two chamfers, and the slider 24 has two chamfers. A stop plate 25 is fitted along the shaft 3d and is set upstream of the slider 24, a spring 26 is set between the stop plate 25 and the slider 24, and a spring 26 is set downstream of the shaft 3d. A nut 27 allows the position of the slider 24 on the shaft 3d to be adjusted.

Note that, as described above, since the brush 23 of the slider 24 is slid on the circuit pattern of the potentiometer 18 to detect the amount of movement of the moving member 3, the amount of movement of the moving member 3 is detected.
It is necessary to prevent rotation about the central axis. Therefore, the end of the rivet 28 provided by tightening or screwing at the tip of the protrusion 7a extending upstream from the end of the retainer 7 that holds the bearing parts 6a, 6b is inside the inner cylinder 3c of the moving member 3. By configuring it to slide within the guide groove 3cl formed linearly along the movement direction on the peripheral wall surface,
Rotation of the moving member 3 is prevented.

The housing lc includes a cover 1cl that accommodates a potentiometer 18 and the like set on the downstream side of the partition wall 1b5;
A rib 1c2 supporting this cover 1cl is integrally formed. The cover 1cl has a bell-like shape with an open end 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 1cl has an inner diameter that almost matches the outer diameter of the raised portion 1b8 formed on the housing lb side, and a stepped portion 1cll is formed on the inner diameter side of the opening end. , an annular space in which an O-ring 29 is provided to ensure a seal between the raised portion 1b8 and the opening of the cover 1cl. Further, the rib Lc2 extends in the direction of the central axis of the housing 1c and is smoothly connected to the outer peripheral surface of the cover 1cl. The ribs 1c2 are composed of four ribs corresponding to the ribs lbl set on the housing 1b.
The downstream side of bl and the upstream side of rib IC2 of the housing IC are aligned so that the cross-sectional shape of the assembly of both ribs lbl and 1c2 forms a streamlined shape (see Fig. 9), to minimize air flow. I try not to cause any breakage.

Therefore, the cover 1c5 constitutes a potentiometer chamber 30 in which the potentiometer 18 and the like are housed.
The end of the shaft 3d, which has a slider 24 provided with a brush 23 that slides on the circuit pattern, is displaced on the central axis according to the movement of the moving member 3. One end of the pin 15, that is, the end that is electrically connected to the lead wire 14b1 of the intake air temperature sensor 14 and the potentiometer 18,
It protrudes into the potentiometer chamber 30.

In addition, in order to improve the assembly precision of the housing 1b and the housing IC in the rotational direction, the rib 1c2 of the housing 1C is
A protrusion 1c3 is set on one of the ribs 1c2 on the end face side connected to the housing 1b on the housing lc side,
Further, a groove 1b9 corresponding to the projection 1c3 is formed in the housing 1b along the inner circumferential wall surface within the rib lbl of the housing 1b on the end face side where the housing 1c is connected to one of the ribs lbl of the housing 1b.

゛ In the air flow measuring device 100 having the above configuration, when a predetermined air flow IQ flows through the air flow path 2, a pressure difference is generated upstream and downstream of the moving member 3, and the moving part tfa resists the pressing force of the spring 11. Then, it moves directly downstream from the fully closed position regulated by the fully closed stopper 1a2, expanding the air passage area between the outer edge 3a of the moving member 3 and the inner peripheral wall surface 1al of the housing 1a, and The moving member 3 moves to a position where the pressure applied to the upstream side surface of the moving member 3, which corresponds to the air passage area necessary for the flow of the flow rate Q, and the pressing force of the spring 11 are balanced. Then, 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 this displacement amount χ
The brush 23 of the slider 24 set at the downstream end of the shaft 3d is now displaced on the circuit pattern of the potentiometer 18, and the amount of displacement χ is the same as that of the potentiometer 18.
The signal is converted into an electrical signal and output to the outside via the bin 15. Here, there is a predetermined functional relationship between the air flow rate Q and the air passage area, and a predetermined functional relationship is established between this air passage area and the amount of movement of the moving member 3, that is, the moving distance of the moving member 3. Inner peripheral wall surface 1a of housing 1a
Since l is adjusted, the electrical signal converted by potentiometer 18 will represent the air flow rate Q.

In addition, in the above configuration, air ventilation between the inside and outside of the air damper chamber 10 is only through the clearance between the outer cylinder 3b of the moving member 3 and the large cylindrical part 1b2 fixedly set on the housing 1b. , vibration of the moving member 3 due to pulsation of the air flow is suppressed, and fluctuations of the moving member 3 are stabilized even in response to stepwise changes in the air flow rate, and behavior such as excessive overshoot of the moving member 3 is prevented. suppressed.

Therefore, according to the above configuration, since the movement of the moving member 3 is linear parallel to the flow of air 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 area to the high flow area, that is, the change in the displacement amount of the shaft 3d, to be uniform, and constant measurement is possible regardless of changes in the flow rate state. Accuracy will be obtained.

In addition, a damper mechanism is used to suppress vibrations due to pulsation of the airflow of the moving member 3 and excessive overshoot when the air flow rate suddenly changes, and the amount of displacement of the shaft 3d connected to the moving member 3 is converted into an electrical signal. The potentiometer 18 is connected to the flow pipe 1
Since it is set within the vane type, it can be made sufficiently smaller and more compact in shape than the vane type, and therefore it is easier to mount it on a vehicle.

Also, the potentiometer 18 is set in the air flow path 2,
Since the data representing the air flow rate is extracted as an electrical signal, it is extremely easy to ensure sealing between the air flow path 2 and the external space.

Further, in the above configuration, each housing la, lb.

1c (especially the inner peripheral wall surface 1a of the housing 1a)
1) Since the outer cylinder 3b and the large diameter cylinder part 1b2 for configuring the moving member 3 and the air damper chamber 10 have a circular cross-sectional shape, sufficient dimensional accuracy can be achieved by molding compared to a square shape or the like. can be ensured, so additional machining after molding is not required, and the number of manufacturing steps can be reduced.

Further, in the above configuration, the ribs lb1. of the housings lb, lc.
Since the assembly of 1c2 is formed into a streamlined shape, the rib l
Disturbance of the air flow due to bl and 1c2 is sufficiently suppressed.

In addition, the above configuration covers 101 potentiometers per day.
The potentiometer 18 is housed in the potentiometer chamber 30 so that the air flow does not come into direct contact with the potentiometer 18, so that foreign matter, moisture, etc. in the air are prevented from adhering to the potentiometer 18. In the above embodiment installed in an engine, fuel, oil, carbon, etc. from the engine are prevented from adhering to the potentiometer 18, and changes in measurement accuracy and durability are prevented, and the initial characteristics can be sufficiently maintained over a long period of time. become.

FIG. 10 shows another embodiment of the gas flow rate measuring device, in which the same parts as in the above embodiment are given the same numbers and the explanation thereof will be omitted.

In this embodiment, a fully closed stopper 31 for regulating the fully closed position of the movable member 3 is fitted into a stop plate 25 fixed to the shaft 3d on the downstream side of the shaft/receiver 8 of the shaft 3d. is constructed from an elastic material. The downstream end surface of the bearing retainer 7 of the bearing 8 is used as a stop surface.

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

Note that, instead of fitting the fully closed stopper 31 into the stop plate 25, it may be fixed to the shaft 3d on the upstream side of the stop plate 25. Further, by fixing the fully closed stopper 31 so that it can move forward and backward relative to the shaft 3d, the fully closed position of the movable member 3 can be finely adjusted.

What is shown in FIG. 11 is the main part of this embodiment of the gas flow rate measuring device, and shows the clearance between the outer cylinder 3b of the moving member 3 and the large diameter cylindrical part 1b2 of the housing 1b. In this configuration, the large diameter cylindrical portion 1b when the movable member 3 on the outer circumferential wall surface on the downstream side of the outer cylinder 3b is in the fully closed state.
A portion of a predetermined width that faces the inner circumferential wall surface of the outer cylinder 3b is a clearance surface 32 that sets a clearance between the outer circumferential wall surface of the outer cylinder 3b and the inner circumferential wall surface of the large diameter cylindrical portion 1b2.

In other words, the diameter of the outer circumferential wall surface on the downstream side of the outer cylinder 3b forming this clearance surface 32 is made larger by a predetermined width than the other outer circumferential wall surface of the outer cylinder 3b, and furthermore, this clearance surface 3
Only No. 2 is formed with sufficiently higher dimensional accuracy than the other outer peripheral wall surfaces.

With this configuration, the clearance between the outer cylinder 3b and the large-diameter cylindrical portion 1b2, which determines the damping characteristics of this device, and the guaranteed range of the dimensional accuracy of the outer cylinder 3b can be reduced, and stable damping characteristics can be achieved. It becomes extremely easy to obtain. Furthermore, 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 small compared to the size of the outer cylinder 3b, so that the foreign matter that has entered the outer cylinder 3b It is easily removed in response to fluctuations in the movement of the moving member 3, and the risk of the movement of the moving member 3 being impaired due to foreign objects being caught is extremely reduced.

Note that this clearance surface 32 may be set on the large diameter cylindrical portion 1b2 side.

Further, in the above embodiment, the outer cylinder 3b is fitted inside the large diameter cylindrical part 1b2 with a predetermined clearance set, and the large diameter cylindrical part 1
Although it was configured to move within b2, the large diameter cylindrical part 1b
2 may be fitted inside the outer cylinder 3b 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 amount of displacement of the shaft 3d into an electrical signal, but any other sensor may be used as long as it can convert the amount of displacement of the shaft 3d into an electrical signal. For example, it is possible to use a differential transformer, an optical non-contact displacement detection sensor, or the like.

Furthermore, although the above embodiment describes the case where the device is attached to an automobile engine to measure the air flow rate, the present measuring device can also 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
The degree of change in the displacement of d can be extremely easily set to be uniform from the low flow rate region to the high flow rate region, and constant measurement accuracy can be ensured regardless of changes in the flow rate state. It has the excellent effect of becoming
The outer cylinder 3 as the first cylinder is moved by the movement of the moving member 3.
b is displaced along the second cylinder through a small gap with the large-diameter cylindrical portion 1b2 as the second cylinder, so the moving member 3 The damping function works against the movable member 3 to suppress vibrations caused by pulsation of the gas flow and excessive overshoot caused by sudden changes in the gas flow rate. Because of this, there is also the excellent effect that this device can be made small and compact.

Next, the mounting structure of this gas flow rate measuring device 100 will be explained. 1 and 2 show an example of the attachment, and FIG. 2 is a view taken from the direction of entry in FIG. 1. In FIGS. 1 and 2, 200 is the gas flow rate measuring device 1.
This is an air cleaner with a built-in filter that filters the air before measurement at 00. The gas flow rate measuring device 100 is mounted on an air cleaner 200.

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

Of the three housings la, lb, and lc forming the outer frame of the gas flow rate measuring device 100, the central housing 1b has raised joints 1d and Ie formed at both ends, as described above. , surface joint part 1
The portion sandwiched between d and le forms a groove portion 1r having a smooth cylindrical surface with a diameter smaller than that of the joint portions 1d and 1e.

The gas flow measuring device 100 is fixed on the air cleaner 200 in the housing lb. Air cleaner 20
On the fixed surface of the gas flow rate measuring device 100 at 0, there are two first projections on a line perpendicular to the axis of the housing lb. A second stay 201.202 is provided. The first and second stays 201 and 202 are spaced apart from each other by a distance greater than the maximum diameter of the gas flow rate measuring device 100.

1st. A metal lower holder 51 is installed on the second stay 201, 202, and the first end 51a of the lower holder 51 is attached to the upper surface of the first stay 201, and the second protrusion 202 The second end 51b of the lower holder 51 is fixed to the upper surface of the holder 51 with pins 54 and 55, respectively.

The lower holder 51 has both ends 51a and 51b connected to the first side of the air cleaner 200. The shape is parallel to the mounting surface of the second stay 201.202, and the part between both ends 51.51b has an arc shape that fits into the groove 1f forming the outer periphery of the intermediate housing 1b of the gas flow rate measuring device 100. It is formed. Also number 1. The mounting surface of the second stay 201.202 is
The bolts 54 and 55 are formed sufficiently wide in diameter.

A metal upper holder 52 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 part 52a as shown in FIG. 3, and this key is inserted into two locking holes 51al and 51a2 formed in the first end 51a of the lower holder. It is fixed by fitting and locking the parts. Also, the upper holder 52
The other end 52b is fixed to the second end of the lower holder 51 with a screw 53. An arch-shaped 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. Similarly to the lower holder 51, the upper holder 52 is also fitted into a groove 1f formed in the circumferential direction of the housing lb.

Furthermore, since the connector 1b6 is molded on the outer periphery of the housing 1b as described above, a window (not shown) is formed in the upper holder 52 so as not to interfere with the connector 1b6. The ends of both holders 51 and 52 along the circumferential direction are bent to fit the shapes of the joints 1d and 1e so as to wrap around the joints 1d and 1e of the housing.

Therefore, since the widths of the two holders 51 and 52 are approximately as large as the length of the intermediate housing lb, the gas flow rate measuring device 100 can be securely fixed to the air cleaner 200. Furthermore, since the housing 1b is formed with a groove 1f, and the holders 51 and 52 are engaged with the groove 1f, it is possible to eliminate rattling, especially in the axial direction, of the gas flow rate measuring device 100 due to engine vibration. . Also, a U-shaped key portion 52 at one end of the upper holder 52
a to the locking hole 51 of the lower holder using the elasticity of the metal.
Since it can be fixed by fitting it into Al, 51a2, the installation work can be done easily.

Further, an arch-shaped bulge 52 formed on the upper holder 52
The length of the upper holder 52 can be changed by the elastic deformation of c, and the tightening force can be automatically adjusted. The measuring device 100 can be firmly fixed to the air cleaner 200.

In this way, the gas flow rate measuring device 100 can be directly mounted and fixed integrally on the air cleaner 200, and the engine can be made more compact. Further, according to this embodiment, since the recessed portion 203 is formed on the surface of the air cleaner 200 facing the lower holder 51 in accordance with the shape of the lower holder 51 (that is, the shape of the housing 1b), the gas flow rate can be measured. The installation height of the device 100 can be lowered, making it even more compact.

On the other hand, in the air inlet end IA of the housing 1a on the most upstream side of the gas flow rate measuring device 100, a recess IAI is formed over the entire circumference to fit a grommet to prevent movement in the axial direction. There is. The inlet end IA is inserted into the air outlet end 204 of the air cleaner 200 with the grommet 60 fitted into the recess IAI. The air outlet end 204 is formed in a direction perpendicular to the recess 203 of the air cleaner 200, and serves as an outlet for the air filtered by the filter in the air cleaner 200 before measurement.

A grommet 60 is suitably compressed on the inner circumferential wall of the outlet end 204 of the air cleaner 200, and the measuring device 10 is
A stepped portion 204a is formed to prevent insertion of zero.

Next, this grommet 60 will be described. GLO and METSUTRO 0 are made of elastic material such as rubber and have a ring shape.
This cross section is shown in FIG. In Fig. 4, grommet 6
The inner circumferential surface 61 of No. 0 was formed into a smooth cylindrical surface without any protrusions or the like. The diameter of the inner peripheral surface 61 of the grommet 60 before fitting is
It is made slightly smaller than the diameter of the recess IAI on the outer periphery of the housing 1a, and is designed to fit into the housing 1a without a gap due to its elasticity when fitted. In addition, grommet 6
An adhesive may be applied between the housing 1a and the housing 1a. Further, on the outer periphery of the grommet 60, there is a tongue portion 62 as a first raised portion having a diameter larger than the inner periphery of the stepped portion 204a of the air outlet end 204 of the air cleaner 200, and a stepped portion 204.
As a second raised part with the same diameter as a or slightly smaller diameter,
A positioning portion 63 is integrally molded. The tongue portion 62
is located on the upstream side, and the positioning part 63 is located on the downstream side,
When the inlet end IA of the gas flow rate measuring device 100 is inserted into the outlet end 204 of the air cleaner 200, the tongue 62 and the positioning part 63 are sufficiently spaced so that the tongue 62 does not overlap the circumference of the positioning part 63. They are formed at appropriate intervals.

The tongue portion 62 has a cross section that tapers toward the outermost periphery, and its tip □ end 62a is slightly inclined toward the positioning portion 63 even before insertion. Further, the outer peripheral portion 63a of the positioning portion 63 is formed into a smooth cylindrical surface.

When inserting the inlet end IA of the gas flow measuring device 100 into the outlet end 204 of the air cleaner 200, the tongue 62 on the outer periphery of the grommet 60, which is press-fitted into the recess IAI of the gas flow measuring device 100, is compressed. Well, grommet 6
0, the tip 62a of the tongue 62 of the grommet 60 is placed in the outlet end 2 of the air cleaner 200 while being accommodated in the recess IAI.
While being rubbed against the inner circumferential wall of the stepped portion 204a of 04, it faces in the opposite direction to the insertion direction. Due to this compressive deformation of the tongue portion 62, the grommet 60 is compressed in the radial direction and performs a sealing action.
Air exchange with the outside can be completely blocked at the connecting portion between the air cleaner 200 and the measuring device 100.

Additionally, the pressure at the outlet end 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 within the air cleaner 200. By the way, since the tongue portion 62 of the grommet 60 is inclined toward the downstream side, that is, toward the communication 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 presses the inner periphery of the air cleaner 200 even more strongly, thereby improving airtightness during engine operation. In addition, the positioning part 63 formed in the grommet 60 can be used to prevent variations in the inner diameter of the stepped part 204a of the outlet end 204 of the air cleaner 200, misalignment of the axis during assembly, vibration during operation, etc.
Air cleaner 200 and measuring device 1
00 can be restricted in the radial direction. Therefore, the positioning part 63 can keep the deviation of the flow path axis within an allowable range, and the amount of deformation of the tongue part 62 can also be kept almost constant.
The grommet 60 itself has excellent durability, and excellent airtightness can be obtained for many years. Further, as described above, the positioning portion 63 and the tongue portion 62 are configured so that they do not interfere with each other even when the tongue portion 62 is deformed to the maximum, so that the inside of the air cleaner 200 and the external space are always connected to the tongue portion 62.
2, and the above-mentioned external pressure can be applied to the tongue portion 62 during operation to develop strong sealing properties.

In the embodiment described above, in the structure for attaching the gas flow rate measuring device 100 to the air cleaner 200, the installation of the inlet portion of the gas flow rate measuring device 100 having a seal portion and the fixing portion of the gas flow rate measuring device 100 to the air cleaner 200 are performed. Since it is located at a separate location, the work is easier, the ease of assembly is improved, and the structure is simplified.

[Effects of the Invention] As described above, the present invention has the advantage that the gas flow rate measuring device can be directly connected to the box body to form a compact gas passage, and the engine can be made more compact. effective.

In addition, the first raised part formed on the grommet provides excellent airtightness at the mounting part and eliminates rattling in the axial direction, and the second raised part prevents vibrations in directions other than the axial direction. It also eliminates sagging, strengthens the connection with the box, and maintains high measurement accuracy of the gas flow rate measuring device.

[Brief explanation of the drawing]

FIG. 1 is a front view showing an embodiment of the mounting structure for a gas flow rate measuring device according to the present invention, FIG. 2 is a view taken from direction A in FIG. 1, and FIG. Figure 4 is a perspective view of the
5 is a sectional view of a gas flow rate measuring device to which the mounting structure of the present invention is applied, and FIG. 6 is a sectional view of the main part of the figure.
7 is a view as seen from direction B with the housing 1c in FIG. 5 removed; FIG. 8 is a partial sectional view taken along line C-C in FIG. 5; The diagram is D-D in Figure 8.
10 and 11 are cross-sectional views taken along the line, and are cross-sectional views of other embodiments of a gas flow rate measuring device to which the mounting structure of the present invention is applied. l...flow path pipe, la, lb, lc...housing. if... Groove, 2... Air passage, 3... Moving member, 3b... Outer cylinder, 3d... Shaft, 8... Bearing, 1
0... Air damper chamber, 11... Spring, 18...
... Potentiometer, 51 ... First holder, 5
1a...first end. 51al, 51a2...hole, 51b...second end. 52...Second holder, 52a...One end (key part)
. 52b...other end, 52c...bulge, 5,3
54゜55...Screw, 60...Grommet, 62
...first raised part, 63...second raised part, IA・
...Gas inlet opening end, IAI...recess, 100...
・Gas flow measurement device. 200... Box body, 204... Gas outlet opening end.

Claims (5)

[Claims] (1) a gas flow path through which the gas to be measured flows in its axial direction; a moving member set in the gas flow path in a state capable of linear movement along the flow direction of the gas to be measured; a flow path pipe in which the gas flow path is formed so that the cross-sectional area of the flow path increases along the flow direction of the gas to be measured at least in the moving range of the moving member; a shaft extending along the flow direction of the measurement gas; a bearing fixedly set in the gas flow path and supporting the shaft in a movable state according to movement of the moving member; a pressing member that applies a pressing force to the moving member in a direction opposite to the flow direction of the gas to be measured; a converting means that converts the amount of displacement of the shaft into an electrical signal; one end is closed by the moving member; a first tube extending along the flow direction of the gas to be measured, the end of which is open; a gas inlet opening end of a gas flow rate measuring device comprising a second cylinder that fits into the first cylinder through a minute gap; and a gas outlet end of a box through which gas before measurement flows. In the mounting structure for a gas flow rate measuring device connected to each other, an elastic member is provided on the outer periphery of one of the gas inlet opening end of the gas flow rate measuring device and the gas outlet opening end of the box body. The grommet is fitted with a first protuberance having an outer circumference larger than the inner circumference of the other of the gas inlet opening end and the gas outlet opening end. , a second protuberance whose outer periphery is approximately the same diameter as the inner periphery of the other opening end is formed, and the grommet is located between the gas inlet opening end and the outlet opening end. The fitted open end is inserted into the other open end, and the first protuberance of the grommet is plastically deformed and comes into contact with the inner periphery of the other open end. Mounting structure of gas flow rate measuring device. (2) The mounting structure for a gas flow rate measuring device according to claim 1, wherein the box is an air cleaner having a built-in filter for filtering gas before measurement. (3) A recess for preventing movement of the grommet in the axial direction is formed on the outer periphery of the open end into which the grommet is fitted. A mounting structure for the gas flow rate measuring device according to any of Item 2. (4) The first raised portion of the grommet is connected to the second raised portion of the grommet.
The gas according to any one of claims 1 to 3, wherein the gas is formed closer to the edge of the opening end to which the grommet is fitted than the raised part of the gas. Mounting structure of flow rate measuring device. (5) Installation of the gas flow rate measuring device according to any one of claims 1 to 3, wherein a cross section perpendicular to the axial direction of the gas flow rate measuring device is circular. structure.