JP4717487B2 - Exhaust flow control valve design method - Google Patents

Description

  The present invention relates to a structure including a torsion coil spring. Specifically, the arm of the torsion coil spring is supported by a first member (for example, a housing) and the side surface of the coil portion of the torsion coil spring is brought into contact with the second member (for example, a valve body), so The present invention relates to a structure in which a second member is urged by force.

A structure that urges a second member (for example, a valve body or the like) in a specific direction by using a torsion coil spring is known. In this type of structure, one arm of a torsion coil spring is usually fixed to a first member (for example, a housing) and the other arm is fixed to a second member (for example, a valve body), and the coil shaft The second member is urged using a moment generated around the second member. In this structure, the amount of movement of the second member is proportional to the biasing force acting on the second member, and the biasing force that biases the second member increases as the amount of movement of the second member increases.
However, there may be a case where non-linearity is required such that the urging force for urging the second member does not change greatly with respect to the movement amount of the second member. For example, in an exhaust passage control valve disposed in an exhaust passage of an internal combustion engine (such as an automobile engine), it is desirable that the urging force does not change with respect to the amount of movement of the valve body. That is, the exhaust flow rate control valve is disposed in the exhaust passage of the internal combustion engine, and is required to open at once when the pressure of the exhaust gas flowing through the exhaust passage becomes a predetermined value or more. For this reason, even if the opening degree of a valve body becomes large, it is requested | required that the urging | biasing force which urges | biases a valve body may not become large.

Therefore, a structure that can suppress an increase in the biasing force acting on the second member with respect to the movement amount of the second member has been developed (for example, Patent Document 1). Patent Document 1 discloses an exhaust passage control valve. The exhaust flow path control valve includes a housing through which exhaust gas flows, a valve body mounted on the housing, and a torsion coil spring that biases the valve body toward the closed side. The torsion coil spring is disposed on the opposite side of the valve body from the housing. The coil portion of the torsion coil spring has a side surface in contact with a spring receiving portion provided substantially at the center of the valve body, and the axis of the coil portion is substantially parallel to the valve body surface. The arm of the torsion coil spring is supported by a spring mounting member, and is slidable in the axial direction with respect to the spring mounting member. In a state where these parts are assembled, when the valve body is displaced to the opening side, the arm is rotationally displaced, and the valve body is urged to the closing side by the bending reaction force of the coil portion generated by the rotational displacement of the arm.
In this exhaust flow control valve, when the valve body is displaced to the open side, the arm of the torsion coil spring slides with respect to the spring mounting member, and the effective length of the arm that causes the bending reaction force of the coil portion (load working radius) The direction of the force acting on the mounting member from the arm changes. Therefore, even if the valve body is displaced to the opening side, an increase in urging force acting on the valve body can be suppressed to a low level. Thereby, when the pressure of the exhaust gas exceeds a predetermined value, the valve is fully opened at a stretch, and a sufficient valve opening can be obtained.
Japanese Patent No. 3326746

  By the way, in the structure in which the side surface of the coil portion of the torsion coil spring is urged against the biased member, a change in load characteristics (so-called change in load characteristics due to sag) accompanying fatigue of the torsion coil spring is a major problem. It becomes. That is, in the structure described above, even if the displacement of the biased member increases, the biasing force of the torsion coil spring does not increase so much. For this reason, when the set load (initial load) decreases due to fatigue of the torsion coil spring, the biased member operates with a low load, and when the biased member operates, the biased member is greatly displaced. It is. Therefore, in the structure described above, when the load characteristic changes due to fatigue of the torsion coil spring, an operation such as replacing the torsion coil spring is required. In addition, when the torsion coil spring is fatigued, the degree of change in the operating characteristics is large, and there is a case where a malfunction occurs and the replacement is necessary in the use process.

  The present invention has been made in view of the above-described circumstances, and an object of the present invention is to provide load characteristics associated with fatigue of a torsion coil spring in a structure that urges a biased member on a side surface of a coil portion of the torsion coil spring. It is to provide a technology that can suppress the change of the level to a level that does not cause a problem.

In order to solve the above problems, an exhaust flow control valve design method disclosed in the present specification is arranged in an exhaust passage of an internal combustion engine, and a closed position for closing the exhaust passage and an open position for opening the exhaust passage. A torsion coil spring that urges the valve element toward the valve closing position, and a spring mounting portion that supports an arm of the torsion coil spring. The spring is formed of an alloy used for a torsion coil spring used in a high-temperature environment, and has a coil portion in which a spring element is wound in a coil shape and arms provided at both ends of the coil portion. The arm is supported by the spring mounting portion so as to be slidable in the axial direction, and the side surface of the coil portion abuts on the valve body, and the valve body is biased toward the valve closing position by the bending reaction force of the coil portion. Pressure of exhaust gas flowing through the exhaust flow path An exhaust flow control valve design method in which a valve body opens when a predetermined value or more is reached, the element wire diameter d of the torsion coil spring, the biasing force Pv of the torsion coil spring in a state where the valve body is moved to the valve closing position, And it has the determination process which determines the distance H of the height direction and the distance W of the horizontal direction from the spring center of a coil part to the support position of an arm in the state which the valve body moved to the valve closing position. In this determination step, the wire diameter d, the biasing force Pv, and the distance H so that the relational expression Pv · W / [d ³ · cos ² {tan ⁻¹ (H / W)}] <86.4 holds. And W are determined.
In addition, a structure (for example, an exhaust flow control valve) disclosed in the present specification includes a first member (for example, a spring mounting portion), a first position (for example, a valve closing position), and a second position (for example, a valve mounting portion). , A valve opening position) and a torsion coil spring that urges the second member toward the first position.
The torsion coil spring includes a coil portion in which a spring element is wound in a coil shape, and arms provided at both ends of the coil portion. The arm is supported by the first member so as to be slidable in the axial direction, and the side surface of the coil portion abuts on the second member, and the second member is directed to the first position by the bending reaction force of the coil portion. Energize.
Here, in a state where the second member has moved to the first position, the biasing force of the torsion coil spring is Pv, the wire diameter of the torsion coil spring is d, and the height from the spring center of the coil portion to the arm support position is high. When the distance in the vertical direction is H and the distance in the horizontal direction is W,
Pv · W / [d ³ · cos ² {tan ⁻¹ (H / W)}] <86.4
The following relational expression holds.
Here, the “distance H in the height direction” is the distance from the spring center of the coil part to the arm support position in the same direction as the direction in which the second member moves when the coil part is viewed from the coil axis direction. I mean.
The “lateral distance W” means the distance from the spring center of the coil portion to the arm support position in the direction perpendicular to the direction in which the second member moves when the coil portion is viewed from the coil axial direction. ing.

  According to this structure, the sag rate of the torsion coil spring can be kept low, and the occurrence of problems caused by the sag of the torsion coil spring can be remarkably suppressed. The reason will be described in detail below.

Generally, the sag of the torsion coil spring is determined by the stress acting on the torsion coil spring and the environmental temperature. In the case of the structure described above, the stress acting on the torsion coil spring is determined by the positional relationship between the spring center of the coil portion and the support position of the arm, the initial load of the torsion coil spring, and the diameter of the coil wire. Among these, the initial load of the torsion coil spring and the diameter of the coil wire cannot be largely adjusted due to restrictions on the apparatus in which the structure is used. On the other hand, the positional relationship between the spring center of the coil portion and the support position of the arm can be adjusted relatively freely, and how to adjust this positional relationship is a big problem. Further, the sag of the torsion coil spring is strongly influenced by the environmental temperature to be used, and proceeds significantly in a high temperature environment.
Therefore, the torsion of the torsion coil spring is most problematic because it is used in a high temperature environment, the initial load of the torsion coil spring is high, the coil wire diameter is limited, and high durability is required. This is the case. In such a case, if the torsion coil spring does not become a problem, the torsion coil spring does not become a problem in other cases. The exhaust flow control valve has a high operating environment temperature of about 600 ° C, the initial load is set to be relatively high, the coil wire diameter is limited due to the compactness of the device, and high durability is required. The Therefore, if the sag does not become a problem under the conditions used for the exhaust flow control valve, it is considered that the sag of the torsion coil spring does not pose a problem in other devices. In particular, the materials of torsion coil springs used in high-temperature environments (for example, Ni-based alloys and Inconel) are different from those of torsion coil springs used at room temperature (for example, piano wires and stainless steel wires). The torsion coil spring used in a high temperature environment has a higher settling rate than the torsion coil spring used at room temperature. For this reason, if the torsion coil spring used in a high temperature environment is suppressed to the extent that it does not become a problem, sag becomes a problem in other general structures (structures used at room temperature). There is nothing.

  Therefore, the present inventor is a torsion coil spring made of a Ni-based alloy actually used for an exhaust flow control valve in an automobile silencer, and the torsion coil spring itself does not need to be replaced and is equipped. The vehicles with a travel distance of 100,000 km or more were collected from the market and the rate of sag was measured. As a result, the sag rate of the torsion coil spring was 9-15%. As a result, it has been found that if the sag rate of the torsion coil spring can be suppressed to 15% or less, it is not necessary to replace the torsion coil spring while the automobile travels 100,000 km. Conversely, if the torsional coil spring sag rate exceeds 15%, the silencer performance deteriorates and the noise reference value cannot be satisfied, and it is found that the silencer itself needs to be replaced. For this reason, if the sag rate of the torsion coil spring can be suppressed to 15% or less, it is not necessary to replace the silencer due to the sag of the torsion coil spring while the automobile travels 100,000 km.

Next, the maximum stress value at which the sag of the torsion coil spring can be suppressed within 15% becomes a problem. According to the study by the present inventor, it has been found that the sag rate of the torsion coil spring used in the exhaust flow control valve and the result of the high-temperature exposure test on the torsion coil spring agree well. For this reason, a high temperature exposure test was performed while changing the load acting on the torsion coil spring, and the maximum stress value at which the sag rate was 15% or less was determined. As a result, it was found that if the stress value of the torsion coil spring is 440 MPa or less, the sag rate can be suppressed to 15% or less.
Since it has been found that the stress acting on the torsion coil spring should be 440 MPa or less, the positional relationship between the spring center of the coil portion and the arm support position, which is such a condition, the initial load of the torsion coil spring, and the coil element The relationship of the wire diameter was determined. In this type of device, the second member is usually biased to the first position in many cases. For this reason, if the stress value in the state in which the second member is biased to the first position (that is, the initial state) is 440 MPa or less, the sag rate can be suppressed to 15% or less. From the formula for obtaining the stress of the torsion coil spring, when the condition for reducing the stress generated in the torsion coil spring to 440 MPa or less with the second member moved to the first position, the following condition must be satisfied. is there.
Pv · W / [d ³ · cos ² {tan ⁻¹ (H / W)}] <86.4
Here, Pv is the biasing force of the torsion coil spring when the second member is in the first position, d is the strand diameter of the torsion coil spring, and H is the height from the spring center of the coil portion to the arm support position. The distance in the direction, W, is the lateral distance from the spring center of the coil portion to the arm support position.
As is clear from the above description, in the structure of the present invention, the stress acting on the torsion coil spring is 440 MPa or less with the second member moved to the first position, and the sag rate is within 15%. Can be suppressed. As a result, it is possible to significantly suppress the occurrence of problems caused by the sag of the torsion coil spring.

In the structure described above, the position of the spring center of the torsion coil spring may be at the same height as the arm support position or at a position lower than the arm support position when the second member is moved to the second position. preferable.
By comprising in this way, it can suppress effectively that the engagement state of the arm of a torsion coil spring and a supporting member will be cancelled | released.

In the structure described above, the second member is provided with a spring receiving portion that receives the coil portion, and the spring receiving portion is at a height from the reference surface of the second member (for example, the surface of the second member). It is preferably offset in the direction.
According to such a configuration, the adjustment allowance for the positional relationship between the spring center of the coil portion and the support position of the arm can be increased, and the degree of freedom in design can be expanded.
Alternatively, the arm of the torsion coil spring may be bent. Even with such a configuration, the adjustment allowance for the positional relationship between the spring center of the coil portion and the support position of the arm can be increased.

Hereinafter, a structure according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a schematic configuration of a structure 10 according to the present embodiment. As shown in FIG. 1, the structure 10 includes first members 12 and 14, a second member 16, and a torsion coil spring 20.
The first members 12 and 14 are a pair of support members, and support the arms 22a and 22b of the torsion coil spring 20, respectively. A through hole 13 is formed in the first member 12, and an arm 22 a of the torsion coil spring 20 is inserted into the through hole 13. The arm 22a is slidable in the axial direction with respect to the through hole 13. A through hole 15 is also formed in the second member 14, and an arm 22 b of the torsion coil spring 20 is inserted into the through hole 15. The arm 22b is slidable in the axial direction with respect to the through hole 15.
The second member 16 can move in the direction of the arrow in the figure (up and down direction), and can move from the initial position to the maximum movement position with respect to the first member. The coil portion 24 of the torsion coil spring 20 is in contact with the upper surface of the second member 16. The second member 16 is subjected to a bending reaction force of the coil portion 24, and the second member 16 is biased toward the initial position (downward).
The torsion coil spring 20 includes a coil portion 24 in which a spring wire is wound in a coil shape, and arms 22 a and 22 b provided at both ends of the coil portion 24. As described above, the arms 22 a and 22 b are respectively supported by the first members 12 and 14, and the side surface (body) of the coil portion 24 is in contact with the upper surface of the second member 16.

2A shows a state where the second member 16 has moved to the maximum movement position, and FIG. 2B shows a state where the second member 16 has been set to the initial position. In the state where the second member 16 is set at the initial position (the state shown in FIG. 2B), the initial displacement is applied to the torsion coil spring 20, and the initial load is applied from the torsion coil spring 20 to the second member 16. Is working. For this reason, even if an upward force acts on the second member 16, the second member 16 does not move from the initial position until the force exceeds the initial load. The initial displacement applied to the torsion coil spring 20 (that is, the positional relationship between the torsion coil spring 20 and the through holes 13 and 15 when the second member 16 is in the initial position) will be described in detail later.
In the state where the second member 16 has moved to the maximum movement position (the state shown in FIG. 2A), the torsion coil spring 20 and the through holes 13 and 15 are compared with the state where the second member 16 is set to the initial position. The positional relationship has changed. That is, the center of the coil portion 24 (spring center) and the support positions of the arms 22a and 22b are changed. Further, as the positional relationship between the torsion coil spring 20 and the through holes 13 and 15 changes, the effective length of the arms 22a and 22b (distance from the coil portion 24 to the through hole 13 (15)) also changes. For this reason, when the second member 16 moves from the initial position to the maximum movement position, the arms 22a and 22b slide (slid) in the through holes 13 and 15 in the axial direction.

FIG. 3 is a diagram showing the relationship between the spring load P generated by twisting the torsion coil spring and the force P _v (biasing force) acting on the second member 16 from the coil portion 24. Since the structure 10 according to the present embodiment is symmetrical with respect to the torsion coil spring 20, only one side of the torsion coil spring 20 is illustrated in FIG.
When the torsion coil spring 20 is twisted as shown in FIG. 3, the spring load P acts on the first member 12 (14) from the arm 22. The direction in which the spring load P acts acts in a direction perpendicular to the line segment connecting the center of the coil portion 24 and the through hole 13 (15). For example, as shown in FIG. 4, the spring loads P1, P2 of the torsion coil spring 20 act in a direction perpendicular to the line segment connecting the center of the coil portion 24 and the action points A, B of the spring loads P1, P2. To do. As is clear from FIG. 4, when the position (arm length) on which the spring load P acts changes, the load direction also changes.

As shown in FIG. 3, when the angle formed by the spring load P and the first member 12 (14) is θ, P cos θ is used as a force for urging the second member 16 downward. Therefore, the force _Pv for urging the second member 16 downward varies not only with the spring load P of the torsion coil spring 20 but also with the angle θ. The angle θ varies depending on the positional relationship between the center of the coil portion 24 and the arm support position (through holes 13 and 15). That is, if the distance in the height direction between the center of the coil portion 24 and the arm support position is H, and the distance in the horizontal direction is W, the angle θ is tan ⁻¹ (H / W).
FIG. 5 is a graph showing a change in the angle θ when the center of the coil portion 24 and the support position of the arm 22 are changed. In the drawing, the vertical axis represents θ, and the horizontal axis represents [H / D (radius D of coil portion 24)]. As for the distance H in the height direction, the point at which the center of the coil part 24 is at the same height as the arm support position is 0, and when the center of the coil part 24 is shifted upward (+), When the center is shifted downward, (−) is taken. As is clear from FIG. 5, when the center position of the coil portion 24 changes, the angle θ changes continuously. Further, the angle θ increases as H / D increases from “0”. For this reason, as the H / D moves away from “0”, the ratio of the spring load P contributing to the urging force of the second member 16 decreases.
If the position of the 2nd member 16 changes, the position of the coil part 24 will change, Therefore The angle (theta) will also change continuously by the position of the 2nd member 16 changing. Accordingly, the relationship between the position of the second member 16 and the urging force acting on the second member 16 has nonlinearity.

FIG. 6 also shows the spring characteristics of a structure according to an example of this embodiment and the spring characteristics of a structure using a pressing spring (compression coil spring). The spring specifications were adjusted so that both structures had the same initial load. As is clear from FIG. 6, in the structure of the present embodiment, an increase in the reaction force (the urging force acting on the second member) is suppressed even when the stroke amount (the amount of movement of the second member) increases (so-called “so-called”). , Lower spring constant), and its load characteristics are non-linear. On the other hand, in the push spring structure, the reaction force increases in proportion to the increase in stroke amount, and shows a linear load characteristic.
Table 1 shows the specifications of the springs used to obtain the measurement results shown in FIG. As is clear from Table 1, according to the structure of the present embodiment, the coil diameter is small and the mass is small as compared with the push spring structure. For this reason, according to the structure concerning this embodiment, space saving and weight reduction will be achieved.

As is clear from the above description, the angle θ changes when the positional relationship between the center of the coil portion 24 and the arm support position (through holes 13, 15) changes, and the required biasing force is obtained when the angle θ changes. The spring load also changes. When the spring load changes, the bending moment acting on the spring element changes, and the stress acting on the spring element also changes. The stress acting on the spring wire is preferably used in a low stress region as much as possible from the standpoint of spring sag and durability. In particular, when used in a high temperature environment, even if a spring material with excellent heat resistance is used, the amount of sag (sag rate) varies greatly depending on the operating stress.
FIG. 7 shows the stress acting on the spring wire of the torsion coil spring 20 when the center of the coil portion 24 is changed with respect to the arm support position while causing the same urging force to act on the second member 16. It is a graph showing a change. In the figure, the vertical axis represents stress, and the horizontal axis represents [H / D (radius D of coil portion)]. Further, regarding the distance H in the height direction, the point where the center of the coil part 24 is at the same height as the arm support position is 0, and when the center of the coil part 24 is shifted upward (+), When the center is shifted downward, (−) is taken. The figure shows the results when the value of W (the lateral distance from the center of the coil portion 24 to the arm support position) / D is changed to 1.27, 1.48, and 1.82, respectively. ing.
As is clear from FIG. 7, when H / D is “0” (that is, when the center of the coil portion 24 and the arm support position are at the same height), the stress is minimized and the H / D moves away from 0. The stress increases accordingly. This is because when the H / D is away from “0”, the angle θ formed by the spring load direction and the biasing direction increases, and the spring load must be increased in order to obtain a necessary bias force.

  FIG. 8 shows the load loss rate (sag rate) of the spring when the stress shown in FIG. 7 is applied to the torsion coil spring and left in that state at 600 ° C. for 100 hours. As is clear from FIG. 8, when H / D is “0” (that is, when the center of the coil portion 24 and the arm support position are at the same height), the sag rate is minimum, and H / D is “0”. The rate of stagnation increases as you leave. It is shown that there is a correlation between the stress acting on the spring wire and the sag rate. For this reason, when the initial position of the second member 16 is set so that (H / D) changes around “0” (for example, when H / D is set in the range of −0.5 to +0.5). The stress acting on the torsion coil spring 20 can be kept low, and the sag rate can be kept low.

As already described, if the sag rate of the torsion coil spring can be suppressed to 15% or less, the durability (sag) of the torsion coil spring does not become a problem. In addition, as shown in FIG. 9, the sag rate of the torsion coil spring by the high temperature exposure test and the value of the recovered product collected from the market agree well, and the stress of the torsion coil spring is suppressed to 440 MPa or less from the result of the high temperature exposure test. It has already been explained that the droop rate can be suppressed to 15% or less. Further, in the structure 10 described above, since the time during which the second member 16 is located at the initial position is long, the second member 16 acts on the torsion coil spring 20 when the second member 16 is located at the initial position (so-called setting). It has already been explained that it is important to suppress the stress to be reduced to 440 MPa or less.
Here, the procedure for calculating the conditions at the time of setting the stress acting on the torsion coil spring 20 to 440 MPa or less will be described. The relationship between the moment generated in the torsion coil spring and the stress generated in the coil wire is expressed by the following equation.
σ = 32M / πd ³ (1)
Therefore, the condition for the sag rate to be 15% is expressed by the following equation.
440> 32M / πd ³ (2)
On the other hand, when the biasing force acting on the second member 16 when the second member 16 is set to the initial position is Pv, the relationship between Pv and the spring moment M is:
Pv = 2 × Pcos θ, P = M / r (3)
It becomes. Here, P is a spring load, and r is a distance (load action radius) from the center of the coil portion 24 to the arm support position (see FIGS. 3 and 4).
From the above equations (2) and (3), the following equation is derived.
32Pv · r / (2πd ³ · cos θ) <440 (4)
Here, θ = tan ⁻¹ (H / W) and r = W / cos θ are represented (see FIG. 3), and when these are substituted into the above equation (4), the following equation is derived.
32Pv · W / [2πd ³ · cos ² (tan ⁻¹ (H / W))] <440 (5)
Pv · W / [d ³ · cos ² (tan ⁻¹ (H / W))] <86.4 (6)
Therefore, when the second member 16 is in the set position, Pv (initial load), d (diameter of spring element wire), H (height from the center of the coil portion to the arm support position so as to satisfy the above expression (6). If the distance in the direction) and W (the distance in the lateral direction from the center of the coil portion to the arm support position) are set, the sag rate can be suppressed to 15% or less.

FIG. 10 shows a graph of the condition of the above-described formula (6). In the figure, the vertical axis is tan ⁻¹ (H / W) and the horizontal axis is Pv · W / d ³ . The region satisfying the expression (6) is a region above the line indicated by f3 and below the line indicated by f4. For example, when the initial load Pv, the lateral distance W between the coil portion 24 and the arm support position, and the diameter d of the coil wire are determined, tan ⁻¹ (H / W) is determined from the region of FIG. The distance H in the height direction between the coil portion 24 and the arm support position can be determined based on the above. FIG. 11 shows the condition of the equation (6) when the initial load Pv is 30 [N] and d is 2.4 [mm].

  In addition, as shown in FIG. 16, when the position of the coil part 24 (2nd member 16) changes with respect to the 1st member 12 (14), the effective length X of the arm 22 will change. FIG. 15 shows a change in the effective length X of the arm 22 when the coil portion 24 is changed with respect to the arm support position. As apparent from FIG. 15, when the center of the coil portion 24 and the height of the arm support position coincide with each other, the arm effective length becomes the minimum, and when the center of the coil portion 24 is shifted upward or downward, the arm is accompanied accordingly. The effective length X is also increased. Therefore, when the center of the coil portion 24 moves from the lower side of the arm support position to the relative position “0”, the arm effective length X gradually decreases, and the protruding length of the arm 22 from the through holes 13 and 15 gradually increases. It becomes long. Further, when the center of the coil portion 24 moves from the relative position “0” to above the arm support position, the arm effective length X gradually increases, while the arm 22 from the through hole 13 (15) becomes The protruding length is gradually shortened. For this reason, from the viewpoint of preventing the arm 22 from coming off from the through hole 13 (15), a range in which the arm protrusion length from the through holes 13 and 15 gradually increases (that is, the center of the coil portion 24 is the relative position “ It is preferable to operate the coil portion 24 in a range below 0 ″.

  Further, when the coil portion 24 moves up and down and the effective length X of the arm 22 changes, the arms 22 a and 22 b slide in the through holes 13 and 15 of the first members 12 and 14 accordingly. The sliding of the arms 22a and 22b causes a hysteresis loop in the forward path and the backward path of the biasing force that biases the second member 16. FIG. 12 shows a result obtained by actually measuring an example of the structure 10 according to the present embodiment. Such hysteresis greatly affects the usage environment (temperature, humidity) and surface properties. From the viewpoint of stability of the load characteristics of the torsion coil spring 20, the hysteresis is reduced (that is, the sliding amount of the arms 22a and 22b is reduced). It is desirable to make it smaller.

FIG. 13 shows a change in the amount of arm sliding when the initial position of the center of the coil portion 24 is changed with respect to the arm support position. In FIG. 13, the maximum movement amount (initial position to maximum movement position) of the second member 16 (coil part 24) is calculated on the assumption that D (the diameter of the coil part 24) / 2. As shown in FIG. 13, when the maximum movement amount is D / 2, the sliding amount of the arms 22a and 22b is the smallest when the initial position of the coil portion 24 is -D / 4.
However, when the maximum movement amount of the second member 16 is different, the initial position at which the sliding amount of the arms 22a and 22b is minimized changes. FIG. 14 shows a change in the optimum initial position (initial position where the sliding amount is the smallest) when the maximum movement amount of the second member 16 is changed. As shown in FIG. 14, when the maximum movement amount is increased, the optimum initial position is also moved to the minus side (the center of the coil portion 24 is downward with respect to the arm support position). As is apparent from FIG. 14, the optimum initial position H ₀ / D is −Smax / 2 with respect to the maximum movement amount Smax. That is, the sliding amount of the arms 22a and 22b can be minimized so that the middle between the initial position and the final movement position is H ₀ / D = 0.

As is clear from the above description, the structure 10 of the present embodiment has the following characteristics.
(1) In the structure 10 in which the arms 22 a and 22 b of the torsion coil spring 20 are supported by the first members 12 and 14 and the second member 16 is biased by the coil portion 24 of the torsion coil spring 20, An increase in the urging force that urges the second member 16 with respect to the movement amount can be suppressed, and a low spring constant can be realized.
(2) When the initial load Pv for biasing the second member 16 is set in advance, the relative position (H / D) of the center of the coil portion 24 with respect to the arm support position is set to −0.5 to +0.5. By setting the initial position of the torsion coil spring 20 within the range, the stress acting on the coil wire of the torsion coil spring 20 can be reduced. Thereby, the sag of the torsion coil spring can be reduced.
(3) Pv · W / [d ³ · cos ² (tan ⁻¹ (H / W))] <86.4 so that the initial load Pv, the coil wire diameter d, and the center and arm of the coil portion 24 are satisfied. By setting the positional relationship (H, W) with the support position, the sag of the torsion coil spring 20 can be suppressed to a level that does not cause a problem even when used under severe conditions such as in a high temperature environment.
(4) when the maximum moving amount Smax of the second member 16 is given, by setting the initial position H ₀ of the coil portion 24 in -Smax / 2, can be minimized hysteresis of the torsion coil spring 20 it can.
(5) By setting the center of the coil portion 24 to be the same height or lower than the arm support position when the second member 16 moves most (when it is at the maximum movement position), the second member 16 It is possible to prevent the arm 22 from coming out of the through holes 13 and 15 of the first members 12 and 14 by the movement.
(6) By using the relative position (H / D) of the center of the coil portion 24 with respect to the arm support position in the range of -Smax to 0, it is remarkable for the durability of the spring, the amount of heat sag, and the prevention of the arm from coming off. Can produce various effects.

  Next, an exhaust passage control valve according to an example using the structure according to the above-described embodiment will be described in detail with reference to the accompanying drawings. The exhaust passage control valve is an exhaust passage control valve that is disposed in an exhaust passage through which exhaust gas from the internal combustion engine flows, and opens when the pressure of the exhaust gas reaches a predetermined value or more. 17 and 18 are perspective views showing an exhaust passage control valve according to this embodiment. As shown in FIGS. 17 and 18, the exhaust flow control valve 50 includes a housing 60, a valve body 70, and a torsion coil spring 40 that biases the valve body 70 toward the housing 60.

Gas discharged from an engine such as an automobile is introduced into the lower end (exhaust pipe connection port) of the housing 60 so that the exhaust gas flows in the housing 60. The upper end (exhaust port) of the housing 60 is closed by a valve body 70 so as to be opened and closed.
Spring mounting portions 62 and 66 are erected on the housing 60. Three spring mounting holes 64 and 68 are formed in the spring mounting portions 62 and 66. The arms 42 a and 42 b of the torsion coil spring 40 are selectively attached to the three spring attachment holes 64 and 68. Therefore, the relative position of the torsion coil spring 40 with respect to the arm support position can be adjusted by selecting the mounting holes for attaching the arms 42a and 42b of the torsion coil spring 40. When the arms 42a and 42b are attached to the spring attachment holes 64 and 68, the arms 42a and 42b are supported slidably in the longitudinal direction with respect to the attachment holes 64 and 68.

  The valve body 70 is a plate molded product manufactured by press molding or the like. The valve body 70 has a spring receiving portion 72 formed at the center thereof, and a pair of grooves 74a and 74b are formed at opposing positions on the outer periphery thereof. The spring receiving portion 72 is formed in a concave shape on the housing 60 side, and is formed in a shape corresponding to the coil portion 41 of the torsion coil spring 40.

  A torsion coil spring 40 is disposed on the opposite side of the valve body 70 from the housing. The torsion coil spring 40 includes a coil portion 41 in which a spring element is wound in a coil shape, and arms 42 a and 42 b formed at both ends of the coil portion 41. The coil portion 41 is held by the spring receiving portion 72 of the valve body 70. When the outer periphery of the coil portion 41 is held by the spring receiving portion 72, the winding axis of the coil portion 41 is substantially parallel to the valve body 70 (the upper surface of the valve body 70).

  The upper end (exhaust port) of the housing 60 is expanded in diameter to form a flange 63, and contacts the lower surface of the valve body 70 at the flange 63. A metal mesh sheet 80 is fixed to the housing 60. The metal mesh sheet 80 includes a seal portion 82 that comes into contact with the flange 63 of the housing 60 and a weld portion 84 that comes into contact with the enlarged diameter portion 61 (R-shaped portion) of the housing 60. The metal mesh sheet 80 is welded to the housing 60 at the weld portion 84 and is not welded at the seal portion 82. That is, since “dentation” and hardening occur at the welded portion, the buffer performance and the sealing performance are deteriorated. For this reason, sealing performance is improved and buffer performance is maintained by not performing welding at the sealing portion 82 that seals the sealing surfaces of the housing 60 and the valve body 70.

FIG. 19 shows the state of the arm 42a (42b) when the arm 42a (42b) of the torsion coil spring 40 is attached to the three spring attachment holes 64 (68). As shown in FIG. 9, it is shown that the spring torsion angle of the arm 42a (42b) increases when the spring mounting hole 64 for attaching the arm 42a (42b) is moved from top to bottom.
FIG. 20 shows the “valve opening-valve opening load” characteristic at the position of each spring mounting hole. When the spring mounting hole is on the upper (-) side, the valve opening load at the time of valve opening can be reduced, while the load operating radius becomes shorter as the valve opening increases, so the valve opening load tends to increase gradually. Is shown. When the spring mounting hole is in the center (regular) position, the valve opening load at the time of valve opening becomes high, but the load acting radius becomes longer as the valve opening increases, so that an increase in the valve opening load is suppressed. The above tendency becomes more remarkable at the position where the spring mounting hole is on the lower (+) side. Therefore, by changing the position of the spring mounting hole 64 (68), the valve opening load at the time of valve opening and the “valve opening-valve opening load” characteristic can be selected.

Even in the exhaust flow path control valve 50 of the above-described embodiment, the initial load Pv and the coil wire are set so as to satisfy Pv · W / [d ³ · cos ² (tan ⁻¹ (H / W))] <86.4. By setting the positional relationship (H, W) between the diameter d and the center of the coil portion 41 and the arm support position, there is a problem with the torsion coil spring 20 even when used under severe conditions such as in a high temperature environment. It can be suppressed to a level that does not become. For this reason, when the exhaust flow control valve 50 of the present embodiment is mounted on an automobile, the occurrence of a decrease in the silencing function due to the torsion of the torsion coil spring before the mileage of the automobile exceeds 100,000 km becomes remarkable. Can be suppressed.

Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.
It should be noted that the technical elements described in this specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology illustrated in the present specification or the drawings achieves a plurality of objects at the same time, and has technical utility by achieving one of the objects.

The figure which shows schematic structure of the structure which concerns on this embodiment. The figure which shows the state (the figure (a)) which the 2nd member moved to the maximum movement position, and the state (the figure (b)) where the 2nd member 16 was set to the initial position. The figure which shows the relationship between the spring load which generate | occur | produces when a torsion coil spring is twisted, and the force (biasing force) which acts on a 2nd member from a coil part. The figure which shows the relationship between the action point of a spring load, and its action direction. The graph which shows the relationship between the relative position of the coil part with respect to an arm support position, and load direction (theta). The graph which shows the relationship between the moving amount (stroke amount) of a 2nd member, and the urging | biasing force which urges | biases a 2nd member. The graph which shows the relationship between the relative position of a coil part with respect to an arm support position, and a spring stress. The graph which shows the relationship between the relative position of the coil part with respect to an arm support position, and a spring sag rate. The graph which shows the change by the exposure time of the sag rate in a high temperature exposure test. The figure which graphed the conditions used as a dripping rate of 15% or less. The figure which graphed the installation conditions from which a droop rate will be 15% or less under specific conditions. The figure which shows the hysteresis measured about the specific example of the structure of this embodiment. The graph which shows the relationship between the relative position of the coil part with respect to an arm support position, and arm sliding amount. The graph which shows the relationship of the optimal initial position with respect to the maximum moving amount. The graph which shows the relative position of the coil part with respect to an arm support position, and the relationship of arm length X. FIG. The schematic diagram for demonstrating that the effective length of an arm changes by the position of the coil part with respect to an arm support position changing. 1 is a perspective view of an exhaust flow control valve according to an embodiment embodying the present invention. FIG. 18 is an exploded perspective view of the exhaust flow control valve shown in FIG. 17. The figure which shows typically the relationship between a spring attachment hole position and the arm angle of a torsion coil spring. The figure which shows the "valve opening-valve opening load" characteristic when an attachment hole position is changed.

Explanation of symbols

··· Structures 12 and 14 · · First members 13 and 15 · · Through hole 16 · · Second member 20 · · Torsion coil springs 22a and 22b · · Arm 24 · · coil portion

Claims (2)

A valve body that is disposed in the exhaust flow path of the internal combustion engine and is movable between a valve closing position that closes the exhaust flow path and a valve opening position that opens the exhaust flow path ;
A torsion coil spring that biases the valve body toward the closed position;
A spring mounting portion that supports the arm of the torsion coil spring,
The torsion coil spring is formed of an alloy used for a torsion coil spring used in a high temperature environment, and a coil portion in which a spring wire is wound in a coil shape, and arms provided at both ends of the coil portion, The arm is supported by the spring mounting portion so as to be slidable in the axial direction, and the side surface of the coil portion abuts on the valve body, and the valve body is attached to the valve closing position by the bending reaction force of the coil portion. And
A design method of an exhaust flow control valve in which a valve element opens when the pressure of exhaust gas flowing through an exhaust passage becomes a predetermined value or more,
Supporting the arm from the wire diameter d of the torsion coil spring, the biasing force Pv of the torsion coil spring when the valve element is moved to the valve closing position, and the spring center of the coil part when the valve element is moved to the valve closing position A determination step of determining a distance H in the height direction and a distance W in the lateral direction to the position;
In the determination step,
Pv · W / [d ³ · cos ² {tan ⁻¹ (H / W)}] <86.4
A design method of an exhaust flow rate control valve, wherein the wire diameter d, the urging force Pv, and the distances H and W are determined so that the following relational expression is satisfied. In the determining step, the wire diameter d, so that the position of the spring center of the torsion coil spring is at the same height as the arm support position or lower than the arm support position in a state where the valve body has moved to the valve open position . 2. The method of designing an exhaust flow control valve according to claim 1, wherein the urging force Pv and the distances H and W are determined .

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