JP5949461B2 - Flow measuring device - Google Patents

Description

  The present invention relates to a flow rate measuring apparatus suitable for measuring, for example, a flow rate of intake air sucked into an internal combustion engine (hereinafter also referred to as intake air amount).

[Conventional technology]
Conventionally, various types of flow measuring devices of this type have been proposed and put to practical use. Recently, the temperature of the intake air (hereinafter referred to as “intake air temperature”) is incorporated into a housing incorporating a flow rate sensor for measuring the amount of intake air. In addition, a flow rate measuring device provided with a temperature sensor for measuring the intake air temperature is also useful (see, for example, Patent Document 1).
This flow measurement device supplies a signal indicating the intake air temperature measured by the temperature sensor together with a signal indicating the intake air amount from the flow sensor to an electronic control device (hereinafter referred to as ECU) that controls the operating state of the internal combustion engine. By doing so, it is used for temperature compensation for appropriately controlling the intake system of the internal combustion engine.

By the way, in order to accurately measure the intake air temperature, it is necessary to attach the temperature sensor in a state where the temperature sensor is exposed from the housing and exposed to the intake air.
In the conventional flow rate measuring device described in Patent Document 1, the temperature of the housing is such that the temperature sensor can protrude into the intake air passage because the housing is sealed to the intake air passage by an O-ring or the like. Usually, a relatively large rectangular insertion hole through which a supporting member (conductive member for connection or terminal) carrying the sensor can pass is provided.
In addition, this relatively large insertion hole needs to be sealed when the housing, which is the lid of the casing, is resin-molded (molded integrally with the casing as an insert product). A rectangular resin molded product is prepared in advance using the (conductive member for connection or terminal) as an insert product, and the housing is resin molded after the above-described insertion hole is sealed with this resin molded product.

[Problems of the prior art]
However, the flow rate measuring apparatus having the above configuration is expensive as a whole because it has many resin molding processes and a large number of parts, and is inexpensive with a novel structure capable of omitting the above-mentioned resin molded product. A flow measuring device is awaited.
In view of this, a proposal has been made to actively utilize the lead wires of the temperature sensor to omit the resin molded product (this is based on the idea of the present inventor and is not well known in the art). That is, this is a method in which a through hole for inserting a lead wire of a temperature sensor is provided in the housing, and the lead wire is inserted into the through hole and then the hole is sealed with an adhesive.

  According to this method, the lead wire itself can be effectively used as a supporting member for the temperature sensor, and the through-hole through which the lead wire is inserted can be made to have a relatively small diameter so that an appropriate amount of adhesive can be filled. Therefore, the through hole can be completely blocked by a simple method of filling the adhesive. Therefore, the resin mold product can be omitted.

  However, according to the subsequent experiments and researches of the present inventor, it has been found that there is a possibility that a conduction failure may occur in an environment where the thermal cycle is severe. In addition, as a result of investigating the cause, it is caused by the occurrence of a crack near the through hole through which the lead wire of the temperature sensor is inserted, and moisture entering the housing through the crack. Also turned out. According to experiments, heat-resistant resin such as PBT (polybutylene terephthalate resin) is generally used for the casing, so a general-purpose epoxy resin-based adhesive with good sealing performance and high heat resistance is used. When it was used, when the cooling / heating cycle was repeated, it was confirmed that a crack occurred in the vicinity of the through hole due to the difference in thermal expansion coefficient between the two members.

JP 2010-181354 A

  The present invention has been made in view of the above circumstances, and its purpose is to ensure high quality without cracking in a housing even in a severe environment of a thermal cycle while having an inexpensive configuration. An object of the present invention is to provide a flow measuring device capable of

[Means of Claim 1]
According to the first aspect of the present invention (flow rate measuring device), the temperature sensor attached to the housing is exposed to the air flowing through a predetermined passage (intake air passage), and from both ends of the temperature detection element. The heat-resistant resin housing has a pair of through-holes through which the lead wire can be inserted from the outside to the inside of the housing, and a housing in each of the through-holes. A pair of adhesive filling holes that are continuously filled with adhesive and the thermal stress that is located between the pair of adhesive filling holes and that is recessed from the inside to the outside of the housing A pair of adhesive filling holes that have absorption grooves and through which lead wires are inserted are filled with an adhesive .

According to the invention of claim 1 having the above-described configuration, even if thermal stress is generated based on a difference in thermal expansion between the casing and the adhesive, the thermal stress absorbing gap formed between the pair of adhesive filling holes. Thermal stress can be absorbed by expansion and contraction of the groove. Therefore, a crack does not occur in the housing even under a severe environment of the cooling and heating cycle.
In addition, the structure is simple enough to provide a thermal stress absorbing groove, and since this groove can be formed integrally during resin molding of the housing, no special man-hour is required to provide the thermal stress absorbing groove. .
Therefore, it is possible to provide a flow rate measuring device that can ensure high quality even in a severe environment of a cooling and heating cycle with an inexpensive configuration.

It is sectional drawing with which it uses for description of the basic function of the flow measuring device for internal combustion engines which shows the representative example of the flow measuring device to which this invention is applied (Example). It is a front view of the said flow measuring device (Example). It is a top view of the housing | casing in the said flow volume measuring apparatus (Example). It is a disassembled perspective view of the said flow measuring device (Example). It is an expanded sectional view which follows the VV line of FIG. 2 (Example). BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram for explaining a main part of the present invention, in which FIG. It is a principal part front view (Example).

  Hereinafter, the best mode for carrying out the present invention will be described in detail according to embodiments shown in the drawings.

The present embodiment shows an application example to a flow measurement device for measuring the intake air amount of an internal combustion engine as a representative example of the flow measurement device of the present invention. In the following description, first, the basic configuration and functions of the flow rate measuring device are outlined, then the detailed configuration and operational effects of the present invention are described in detail, and finally, the modified examples of the characteristic items of the present invention are summarized and enumerated. To do.
In each figure, the same or equivalent parts are denoted by the same reference numerals, and redundant description is omitted.

[Configuration of Example]
First, the basic configuration and function of the flow measurement device of the present invention will be described with reference to FIGS.

The flow rate measuring device 1 is for measuring the flow rate (intake amount) of intake air taken into the internal combustion engine, and is disposed in an intake air passage (hereinafter referred to as an intake passage) 2. A housing 3 of the flow rate measuring device 1 accommodates a thermal type flow rate sensor 4 that measures the amount of intake air, and is provided with a temperature sensor 5 for measuring the temperature of intake air (intake air temperature).
Then, by supplying a signal indicating the intake air temperature measured by the temperature sensor 5 together with a signal indicating the intake air amount from the flow sensor 4 to an ECU (not shown) that controls the operating state of the internal combustion engine, Used for temperature compensation to properly control the intake system of the engine.

  The flow rate measuring device 1 has the following specific configuration including the flow rate sensor 4 and the temperature sensor 5 described above.

  The housing 3 is formed of a general heat-resistant resin, for example, PBT (polybutylene terephthalate resin), and a main body 31 that is airtightly attached to the intake passage 2 and a main body 31 that hangs down from the main body 31 and enters the intake passage 2. It is comprised from the flow-path formation part 32 protruded. In addition, as shown in FIG. 4, the housing 3 has a disk shape with the main body 31 having a flange portion 31 a, whereas the flow path forming portion 32 has a rectangular parallelepiped box shape. The flow path forming unit 32 is formed with a bypass flow path 33 that takes in a part of the intake air flowing through the intake path 2 and flows the flow sensor 4 in the bypass flow path 33.

  The bypass passage 33 has an intake air intake port 33a that opens toward the upstream side of the intake passage 2 and an intake air discharge port 33b that opens toward the downstream side of the intake passage 2, for example, The intake air taken in from the intake port 33a as shown by the arrow X is circulated as shown by the arrow Y and is released from the discharge port 33b. Further, a dust discharge path 34 for discharging dust is connected to the bypass flow path 33. Since this dust discharge path 34 faces the intake port 33a and is located on the upstream side of the flow rate sensor 4, the dust that has entered the bypass flow path 33 does not go to the flow rate sensor 4, but is indicated by the arrow Z. In this way, it returns to the intake passage 2 through the dust discharge passage 34.

The flow rate sensor 4 protrudes in a region where the intake air flows in a direction opposite to the flow in the intake passage 2 (arrow Q = X) in the bypass flow path 33.
As shown in FIG. 4, the flow sensor 4 includes a signal processing unit (not shown) that performs predetermined processing on the generated signal, and another terminal 7 that electrically connects the terminal 6 and the signal processing unit. In addition, the sensor assembly 8 is configured by resin molding as an insert product. The sensor assembly 8 is loaded into the assembly mounting hole 9 provided in the central portion of the main body 31 of the housing 3 by, for example, press-fitting so that the flow sensor 4 protrudes into the bypass flow path 33.

The temperature sensor 5 has a temperature detection element 5a exposed to the air flowing through the intake passage 2, and a pair of lead wires 5b extending from both ends of the temperature detection element 5a. For example, a known thermistor is used as the temperature detection element 5a. The temperature sensor 5 is attached to the main body 31 of the housing 3, particularly its flange 31 a, which will be described later, separated from the flow path forming portion 32 so as not to be affected by the heat from the flow path forming portion 32. It is suspended by means 50.
The flange 31a is provided with an annular groove 31b for loading the seal member (O-ring) 10 on the outer periphery, and the housing 3 is hermetically sealed via the seal member 10 in the mounting hole 2a of the intake passage 2. It is installed.

The terminal 6 is an output terminal of the flow rate measuring device 1, and is held by a holder 11 bulged on the upper surface of the main body 31 of the housing 3, and the tip of the lead wire 5 b of the temperature sensor 5 The terminal 7 protruding from the sensor assembly 8 is electrically connected.
The terminal 6 is resin-molded as an insert product together with the housing 3 and the sensor assembly 8, and a connector 20 for outputting a signal indicating the intake air amount and the intake air temperature to the ECU is configured (hereinafter referred to as the housing 3, A resin portion formed by resin molding using the terminal 6 and the sensor assembly 8 as inserts is referred to as a housing 21. The housing 21 includes the resin portion of the connector 20.)

  Next, the mounting means 50 of the temperature sensor 5 will be described in detail with reference to FIGS. 4 and 5 as well.

A pair of small-diameter through-holes 51 and a large-diameter and elliptical adhesive filling hole 52 are provided in the flange 31a of the main body 31 of the housing 3 so as to linearly penetrate in the thickness direction. ing. Each through hole 51 allows each lead wire 5b of the temperature sensor 5 to be inserted from an opening 51a on the lower side (outside of the housing 3) to an opening 51b on the upper side (inside of the housing 3). The agent filling hole 52 is connected to the opening 51b above each through hole 51 (inside the housing 3), and is filled with the adhesive after the lead wire 5b is inserted. As this adhesive, a general-purpose adhesive having a high sealing property and a high heat resistance, for example, an epoxy resin adhesive is used, and the lead wire 5b can be firmly fixed to the flange portion 31a by this adhesive.
The adhesive filling hole 52 promotes the filling of the adhesive into the through-hole 51 and, at the same time, increases the bonding area of the lead wire 5 b and supplements the fixing of the lead wire 5 b in the through-hole 51.

  In addition, a guide portion 53 that guides the lead wire 5 b when the lead wire 5 b is passed through the through hole 51 is bulged and formed in the flow path forming portion 32 of the housing 3. The guide portion 53 is provided with a press-fit grip 53a capable of temporarily fixing the lead wire 5b on the lower end side, and can hold the lead wire 5b after passing the lead wire 5b through the through hole 51. . Therefore, even before the lead wire 5b is fixed with the adhesive, the temperature sensor 5 does not fall off.

  Furthermore, a rectangular thermal stress absorbing groove 54 is formed in the flange portion 31a of the casing 3 between the pair of adhesive filling holes 52 and is formed to be recessed from the inside to the outside of the housing 3. Is provided. The relationship between the rectangular thermal stress absorbing groove 54 and each hole of the elliptical adhesive filling hole 52 is that the volume of the thermal stress absorbing groove 54 is A, and the volume of each adhesive filling hole 52 is as follows. When B is B, the relationship of A> B is satisfied.

[Effects of Examples]
According to the flow rate measuring apparatus 1 configured as described above, the housing 3 is provided with the through hole 51 that communicates the inside and outside of the housing 3, and the lead wire 5 b of the temperature sensor 5 is directly inserted into the through hole 51. The lead wire 5b is fixed to the housing 3 with an adhesive. The leading end of the lead wire 5 b that has passed through the through hole 51 is electrically connected to a terminal (output terminal) 6 that constitutes the connector 20.

  As a result, the lead wire 5b itself can be effectively used as a support member for the temperature sensor 5. For example, the terminal 6 does not need to protrude from the flange 31a of the housing 3 to the intake passage 2. Moreover, since the through hole 51 through which the lead wire 5b is inserted can be made small enough to be filled with an appropriate amount of adhesive, the through hole 51 can be completely sealed by a simple method of filling the adhesive.

  In addition, the through hole 51 is provided with an adhesive filling hole 52 connected to the opening 51 b located inside the housing 3, and the adhesive filling hole 52 fills the through hole 51 with the adhesive. At the same time, the bonding area of the lead wire 5b is increased to supplement the bonding and fixing of the lead wire 5b in the through hole 51.

  By the way, the housing 3 and the adhesive are completely different from each other, and the heat expansion resin such as PBT has a much larger thermal expansion coefficient than the epoxy resin adhesive. For this reason, in the severe environment of the thermal cycle, the vicinity of the adhesive filling hole 52 is caused by the thermal stress generated based on the thermal expansion difference between the casing 3 and the adhesive filled in the adhesive filling hole 52. Cracks may occur.

In this embodiment, since the thermal stress absorbing groove 54 is provided between the pair of adhesive filling holes 52, thermal stress can be absorbed by expansion and contraction of the thermal stress absorbing groove 54. Therefore, no crack is generated in the housing 3 even in an environment where the heat cycle is severe.
The mold resin may intervene in the thermal stress absorbing groove 54 when the housing 21 is resin-molded on the housing 3. In this case, the mold resin does not completely fill the groove 54, and even if the mold resin is completely filled, the housing 3 and the mold resin are separate members, so that the thermal stress can be absorbed by the groove 54.

  Here, the relationship between each hole of the adhesive filling hole 52 and the thermal stress absorbing groove 54 is determined from the volume B of the hole 52 in consideration of the amount of the adhesive filled in the adhesive filling hole 52 and solidified. It is important that the volume A of 54 is larger (a relation of A> B is satisfied), and an example of the structure is shown in FIG.

6A and 6B, the dimensional relationship between the rectangular thermal stress absorbing groove 54 and the elliptical adhesive filling hole 52 is that the length in the longitudinal direction of the groove 54 is L, and the depth is If H is the length of the hole 52 in the long axis direction and l is the depth, the relationship of L> l and H> h is satisfied.
As a result, the volume relationship between the rectangular thermal stress absorbing groove 54 and the elliptical adhesive filling hole 52 can satisfy A> B.

In addition, according to the thermal stress absorbing structure of the present invention, the thermal stress absorbing groove 54 is simple, and the groove 54 can be integrally formed when the casing 3 is molded with resin. The number of steps for providing the stress absorbing groove 54 is not particularly required.
Therefore, it is possible to provide the flow rate measuring device 1 that can ensure high quality with an inexpensive configuration even in a severe environment of the cooling and heating cycle.

[Modification]
In addition, the aspect of the attachment means 50 of the temperature sensor 5 is not limited to the above-described embodiment, and can be variously modified without departing from the spirit of the present invention.

As an example of the modification,
(1) When the thermal stress absorbing groove 54 is rectangular and the adhesive filling hole 52 is elliptical as in the above embodiment, the surface area of the groove 54 is C, and the hole 52 When the surface area of D is D, the relationship of C> D may be satisfied. However, A> B, only in one of the lengths L and l or the depths H and h of the groove 54 and the hole 52, or only in the short direction of the groove 54 and the length in the short axis direction of the hole 52, You may make it adjust the relationship of C> D.
(2) Both the adhesive filling hole 52 and the thermal stress absorbing groove 54 may have the same form (rectangular shapes, elliptical shapes).
(3) Depending on the filling amount of the adhesive, the through hole 51 and the adhesive filling hole 52 may be used as a single through hole (51, 52).
(4) The thermal stress absorbing groove 54 may be divided into a plurality.

  The flow rate measuring apparatus 1 of the present invention is not limited to the application example of the above-described embodiment, but can be applied to various uses other than the use of measuring the intake air amount taken into the internal combustion engine of the vehicle. It is.

  DESCRIPTION OF SYMBOLS 1 ... Flow measuring device, 2 ... Intake air passage (predetermined passage), 3 ... Housing, 4 ... Flow rate sensor, 5 ... Temperature sensor, 5a ... Temperature detection element, 5b ... Lead wire, 33 ... Bypass flow path, 50 ... Attachment means, 51 ... through hole, 52 ... adhesive filling hole, 54 ... thermal stress absorbing groove.

Claims (4)

A bypass passage (33) that takes in a part of the air flowing through the predetermined passage (2) and a flow rate sensor (4) that measures the flow rate of the air that flows through the bypass passage (33) is provided. A formed housing (3);
In a flow rate measuring device (1) comprising a temperature sensor (5) attached to the housing (3) and measuring the temperature of air flowing through the predetermined passage (2),
The temperature sensor (5) has a temperature detection element (5a) exposed to the air flowing through the predetermined passage (2) and a pair of lead wires (5b) extending from both ends of the temperature detection element (5a). And
The housing (3) includes a pair of through holes (51) through which the lead wires (5b) are inserted from the outside to the inside of the housing (3), and the housings in the holes of the through holes (51). Located between the pair of adhesive filling holes (52) that are connected inside the body (3) and filled with the adhesive, and between the pair of adhesive filling holes (52), the housing (3) A thermal stress absorbing groove (54) formed in a shape recessed from the inside toward the outside,
The flow rate measuring device (1) , wherein the pair of adhesive filling holes (52) into which the lead wires (5b) are inserted are filled with an adhesive . In the flow measuring device (1) according to claim 1,
When the volume of the thermal stress absorbing groove (54) is A and the volume of each hole of the adhesive filling hole (52) is B,
A> B
The flow rate measuring device (1) characterized by satisfying the relationship: In the flow measuring device (1) according to claim 2,
When the surface area of the groove for heat stress absorption (54) is C and the surface area of each hole of the adhesive filling hole (52) is D,
C> D
The flow rate measuring device (1) characterized by satisfying the relationship: In the flow measuring device (1) according to claim 2,
When the depth of the heat stress absorbing groove (54) is H and the depth of the adhesive filling hole (52) is h,
H> h
The flow rate measuring device (1) characterized by satisfying the relationship:

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