JP2000257560A - Thin plate valve element and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thin plate valve element provided with sufficiently high durability for repetitive load condition in corrosive atmosphere of a reed valve for a suction and discharge valve device of an air compressor and being subjected to repetitive bending load by finding a proper selection method for a material by taking such corrosion environment into account. SOLUTION: When a thin plate valve element being subjected to bending load of lead valves 5a, 5b for a suction and discharge valve device 9 of a reciprocating compressor is manufactured, a ratio of fatigue strength σw to Young's modulus E of a material of the valve element, σw/E=ε, is employed as fatigue allowance distortion, a ratio of the ε to fatigue allowance distortion εa of a comparison material at a fatigue destruction limit, ε/εa=S.F, is employed as a safety factor, and a material having this safety factor S.F of 1 or more is selected. A material having ε=σw/E of 3.5×10-3 or more is employed as the material of the thin plate valve element.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve body made of a thin plate subjected to a bending load, such as a reed valve for a suction and discharge valve device of a reciprocating compressor, and a manufacturing method including a method for selecting a material of the valve body.

[0002]

2. Description of the Related Art FIG. 3 is a sectional view showing an example of a reciprocating air compressor near an upper portion of a cylinder. In FIG. 3, 10
Is a cylinder in which a piston (not shown) reciprocates on the inner peripheral surface, and 11 is a cylinder lid fixed to the upper part of the cylinder 10 by a plurality of bolts (not shown) and covering the cylinder 10. Inside, suction and discharge gas passages (air passages) 14a and 14b are formed.

Reference numeral 9 denotes a suction and discharge valve device. The suction and discharge valve device 9 is fixed to the cylinder lid 11 by bolts 12 and nuts 13 inserted into two bolt holes 8 (see FIG. 2).

FIGS. 1 and 2 show the structure of the suction and discharge valve device. FIG. 1 is a sectional view in the front direction (a sectional view taken along line AA in FIG. 2), and FIG. 2 is a plan view (D in FIG. 1). FIG.

1 and 2, reference numeral 1 denotes a suction valve seat, and reference numeral 2 denotes a discharge valve seat. The suction valve seat 1 has a root portion fixed to the suction valve seat 1 by a valve support 6a. 5a is connected and disconnected to open and close the suction hole 1a.
The discharge side reed valve 5b fixed to the discharge valve seat 2 at (b) comes into contact with and opens and closes the discharge hole 2a. 7, 7
Is a fixing bolt. 3 is a packing inserted between the suction valve seat 1 and the discharge valve seat 2, and 4 is inserted between the suction valve seat 1 and the discharge valve seat 2, and the two valve seats 1 are provided. 2 are parallel pins for improving the assembly accuracy.

[0006]

In the suction and discharge valve device 9 shown in FIGS. 1 and 2, the reed valves 5a and 5b made of a thin plate have their roots and the valve supports 6a and 6b have bolts 7 and 7 to form a fixed cantilever beam, with the root portion serving as a fulcrum to open and close the suction hole 1a and the discharge hole 2a.

[0007] Therefore, in the suction and discharge valve device 9, the repetition of opening and closing of the reed valves 5 a and 5 b causes repeated bending stress to act on the root thereof, which causes fatigue of the material for the reed valves 5 a and 5 b. When the limit is exceeded, the occurrence of fatigue fracture is observed.

In an air compressor using such a suction / discharge valve device 9, water or chlorine ions (C
l ⁻ ) and corrosive components such as sulfur oxides (SOx) are mixed therein, so that the above-described repetitive bending stress acts in air containing these corrosive components, and the reed valve due to such corrosion fatigue. There is a situation where breakage of 5a and 5b is easily promoted.

Conventionally, in order to cope with the corrosion fatigue as described above, a corrosion-resistant material such as martensitic stainless steel (JIS-SUS420J2) is used as a material for the reed valves 5a and 5b. High corrosion fatigue resistance cannot be obtained.

In the case of thin valve bodies which are subjected to a bending load, such as the above-mentioned reed valve, conventionally, a repetitive fatigue diagram based on the fatigue strength (fatigue limit) of a material for preventing the fatigue failure is used. Although such selection has been made, such a conventional selection method is not sufficient as a material selection method for a thin plate-shaped valve element in consideration of the corrosion fatigue as described above.

The present invention has been made in view of the above-mentioned problems in the prior art, and considers such a corrosive environment in a thin plate-shaped valve body which is repeatedly subjected to a bending load in a corrosive atmosphere such as a reed valve for a suction and discharge valve device of an air compressor. An object of the present invention is to provide a thin plate-shaped valve having sufficiently high durability against repeated load conditions in a corrosive atmosphere by finding an appropriate method for selecting the material.

[0012]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a thin plate-shaped valve body which receives a bending load such as a reed valve for a suction and discharge valve device of a reciprocating compressor. In the above, the valve element has an allowable fatigue strain ε defined by a ratio σw / E = ε between the fatigue strength σw and the Young's modulus E of 3.
A thin plate-shaped valve element characterized by being made of a material of 5 × 10 ⁻³ or more is proposed.

Preferably, in claim 1, the material of the valve body is made of a titanium-based alloy.

A third aspect of the present invention provides a method of manufacturing the thin plate-shaped valve element.
In particular, the present invention relates to a method for selecting a material. In manufacturing a thin plate-shaped valve element subjected to a bending load such as a reed valve for a suction and discharge valve device of a reciprocating compressor, the fatigue strength σw and Young's modulus of the material of the valve element The ratio σw / E = ε with E is defined as the allowable fatigue strain, and the ratio ε / εa = SF of the allowable fatigue strain εa and the allowable strain εa of the comparative material at the fatigue fracture limit is defined as the safety factor. Select a material with a safety factor S / F of 1 or more,
The present invention provides a method of manufacturing a thin plate-shaped valve body, wherein the thin plate-shaped valve body is manufactured using the material.

According to this invention, the ratio σ between the fatigue strength σw and the Young's modulus E of the thin valve body subjected to repeated bending loads is
w / E = ε is defined as the allowable fatigue strain, and the allowable fatigue strain εa = σ of the fatigue fracture limit by the fatigue test under the repeated bending load.
The material for which w / E is obtained is used as a comparative material.

Then, the ratio ε / εa = S of the allowable fatigue strain ε of the material of the thin plate-shaped valve element and the allowable strain εa of the comparative material.
・ F is the safety factor of the valve material, and this safety factor S ・ F
Is selected as a material for the thin plate-shaped valve element.

Then, the extracted value of the allowable fatigue strain at which the safety factor becomes 1 or more is corrected based on the result of the fatigue test by the repeated bending load in the corrosive atmosphere to add the allowable fatigue strain ε (σw / E) in the corrosive environment. ).

According to this procedure, a material having the allowable fatigue strain ε = σw / E of 3.5 × 10 ⁻³ or more is selected as the material of the thin plate-shaped valve element. A titanium alloy is suitable as a material that satisfies the specified value and has high corrosiveness.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to an embodiment shown in the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not merely intended to limit the scope of the present invention, but are merely illustrative examples unless otherwise specified. Absent.

1 and 2 show the structure of a first embodiment of a suction and discharge valve device for an air compressor to which the present invention is applied, and FIG. 1 is a sectional view in the front direction (a line AA in FIG. 2). Sectional view), FIG.
2 is a plan view (a view as seen from an arrow D in FIG. 1). FIG. 3 is a vertical sectional view of the upper part of the air compressor. 4 to 10 are component diagrams of members constituting the suction and discharge valve device, FIG. 4 is a plan view of a suction valve seat, FIG. 5 is a cross-sectional view taken along line BB of FIG. 7 is a plan view of a discharge valve seat, FIG. 7 is a cross-sectional view taken along line CC of FIG. 6, FIG. 8 is a plan view of a reed valve, FIG. 9 is a plan view of a valve support, and FIG. .

In FIGS. 1 and 2 and FIGS.
Is a disc-shaped suction valve seat, 2 is a disc-shaped discharge valve seat, and the suction valve seat 1 and the discharge valve seat 2 are connected between the two by reed valves 5a, 5b and valve supports 6a, which will be described later. 6b is fixed to the cylinder lid 11 by bolts 12 and nuts 13 (see FIG. 3) inserted into the two bolt holes 8 at the two positions. 3 is inserted between the suction valve seat 1 and the discharge valve seat 2,
This packing seals the outer peripheral side. The suction valve seat 1 is provided with a plurality of suction holes 1a, and the discharge valve seat 2 is provided with a plurality of discharge holes 2a substantially axially symmetric with the suction hole 1a.

5a is a reed valve on the suction side, 6a is a valve support on the suction side, 5b is a reed valve on the discharge side, 6b is a valve support on the discharge side, and the reed valves 5a and 5b are made of an elastic thin plate. The root is held down by the valve supports 6a and 6b, and is fixed to the suction valve seat 1 and the discharge valve seat 2 by bolts 7, 7 inserted into bolt holes 7a, 7a, respectively. Therefore, the reed valves 5a and 5b are fixed at their roots and are formed in a cantilever shape that opens and closes the suction holes 1a and 2a at their free ends, and the plate surfaces of the valve supports 6a and 5b function as stoppers. 6b, the fully open position is regulated.

Numeral 4 denotes a parallel pin which is inserted through the center of the suction valve seat 1 and the discharge valve seat 2 to adjust the positions of the suction valve seat 1 and the discharge valve seat 2 to improve assembly accuracy. Things.

When the air compressor provided with the suction and discharge valve device 9 operates, as shown in FIG.
When the pressure in the cylinder 10 drops to near the negative pressure due to the lowering of the piston (not shown) fitted in the cylinder 0, the pressure difference between the gas passage 14a on the suction side and the inside of the cylinder 10 causes the reed valve 5a on the suction side to move. When opened, low-pressure gas (air) is sucked into the cylinder 10 through the reed valve 5a.

When the piston rises, the gas in the cylinder 10 is compressed. When the pressure in the cylinder 10 exceeds the pressure in the gas passage 14a on the suction side, the pressure difference causes the reed valve 5a on the suction side to close, Further, when the pressure in the cylinder 10 exceeds the pressure in the discharge-side gas passage 14b due to the rise of the piston, the discharge-side reed valve 5b opens. Then, the compressed gas (compressed air) from the inside of the cylinder 10 is supplied to the use destination through the reed valve 5b and the gas passage 14b.

The above configuration and operation are the same as in the prior art. In the embodiment of the present invention, the reed valve 5a,
5b is improved.

That is, as described above, the suction side reed valve 5a
The reed valve 5b on the discharge side is made of a thin elastic plate-like body.
Are fixed to the suction valve seat 1 through the valve or to the discharge valve seat 2 through the bolt 7 and the discharge-side valve support 6b. In the embodiment of the present invention, the reed valve 5a,
As the material of 5b, a material having a ratio of the fatigue strength σw to the Young's modulus E (σw / E) of 3.5 × 10 ⁻³ or more is used. Then, a titanium-based alloy is used as a preferable specific material. Hereinafter, the reason will be described.

Destruction of a member to which bending stress repeatedly acts like the reed valves 5a and 5b is determined by the magnitude of the applied stress amplitude σa and the fatigue strength σw of the member. The safety factor S · F of the member is defined by the following equation (1). S · F = σw / σa (1) Here, σa can be obtained from the strain amplitude εa occurring in the reed valves 5a and 5b and the Young's modulus E of the material. By substituting this relationship into equation (1), S ・ F = σw / (εa ・ E) (2) This relationship is also expressed as: SF = (σw / E) / εa (3) Here, if (σw / E) = εw is defined as the allowable fatigue strain, the above equation (3) is given by: S · F = εw / εa (4) The above equation (4) expresses SF by distortion. In other words, it can be seen that in a system with constant deformation, it is desirable to display the intensity on a strain basis.

Here, the conventional reed valves 5a and 5b made of martensitic stainless steel (JIS-SUS420J2, hereinafter abbreviated as SUS) have a certain degree of damage but can be used for a long time without being damaged. From this, it can be considered that the safety factor S · F is close to 1.

Therefore, if S · F = 1 is substituted into the above equation (3), the distortion ε generated at this time in the reed valves 5a and 5b
a is as follows: εa = (σw / E) _SUS (5) Εa in the above equation (5) is the allowable fatigue strain of the reed valves 5a and 5b made of the SUS material. As a result, the safety factor S · F of any material is given by the equation (3) and the equation (5).
From the equation, SF = (σw / E) / (σw / E) _SUS (6), and the allowable fatigue strain of various materials (σw / E) and the allowable strain of SUS material (σw / E) _SUS As a ratio of

The table shown in FIG. 17 shows the reed valve 5a,
For the material applicable to 5b, the fatigue safety factor S · F for the SUS material was obtained from the above equation (6). As is clear from FIG. 17, the safety factor S · F with respect to the SUS material is 1 or more only in a titanium alloy having a high tensile strength σ _B of more than 1000 N / mm ² .

Young's modulus of the titanium alloy E = 106 × 1
0 ³ N / mm ² , the safety factor S ·
F = 1.0 or more fatigue strength σw = 371 N / mm ²
Becomes

Therefore, in air, the reed valve 5a,
As a material 5b, if a material having a fatigue strength σw = 371 N / mm ² or more that provides the safety factor S · F of 1 or more is used, a reed valve 5a having higher fatigue resistance than a conventional SUS material,
5b can be obtained.

The above is based on the fatigue strength of the material for the reed valves 5a and 5b in the air. In the reed valves 5a and 5b, as described above, the corrosive components such as moisture in the air cause Fatigue failure occurs at a stress lower than the fatigue strength. Therefore, the reed valve 5
It is necessary to use fatigue strengths a and 5b in an environment containing the corrosive component, and the effect must be verified in an environment in which the influence of such corrosion can be verified.

From such a viewpoint, the inventors conducted the following experiment and determined the fatigue resistance based on the fatigue strength in the corrosive environment.

[Experimental example] That is, in such an experiment,
Reed valves having the same dimensions as the conventional reed valves 5a and 5b made of a SUS material were manufactured from the four types of titanium alloys shown in FIG.
00 rpm × 20 consecutive days (3.4 × 10 ⁷ repetitions)
Times) fatigue experiments. Then, for comparison, a fatigue test similar to that described above was performed for the conventional reed valves 5a and 5b made of a SUS material.

As a result, the reed valve 5 made of titanium alloy
For a and 5b, four types of JIS shown in FIG.
F = 0.83), and no breakage occurred.
On the other hand, out of the 20 trials, the suction side reed valve 5a made of SUS material was damaged in three, but the discharge side reed valve 5b was not damaged. It is presumed that the reed valve 5a on the suction side was damaged because the corrosive atmosphere was stronger than on the discharge side.

As described above, from the SUS material that has been damaged
Bending stress generated at the fixed ends of the reed valves 5a and 5b
σ_mxIs the curvature half of the valve supports 6a and 6b used in this experiment.
The diameter R is 140 mm, and the thickness h of the reed valves 5a and 5b is h = 0.
508 mm_mx= Eh / 2R = (206 × 10^-3× 0.508) / (2 × 140) = 373.7 N / mm²  Becomes

FIG. 17 shows this value (373.7 N / mm ² ).
SUS material, ie, martensitic stainless steel (S
US420F2) fatigue strength σw (715 N / mm ² )
In comparison with, the actual reed valves 5a and 5b are broken at a value considerably smaller than the fatigue strength in air. This is due to the influence of corrosion, which determines the strength of the reed valves 5a and 5b to which the corrosion fatigue strength is applied. In such a fatigue test, the safety factor S · F = 0.
83 reed valves 5a, 5 made of JIS Class 4 titanium alloy
It is presumed that no breakage occurred in b due to the high corrosion resistance of the titanium alloy.

However, as shown in FIG. 17, a part of the reed valves 5a and 5b made of the JIS type 4 titanium alloy having the allowable fatigue strain: σw / E = 2.9 had abrasion phenomena partially after the experiment was completed. Therefore, as a material for the reed valves 5a and 5b, the allowable fatigue strain of the SUS material: σw / E = ε =
The material must be 3.5 × 10 ⁻³ or more.

FIGS. 11 to 16 show an air compressor according to a second embodiment of the present invention. FIG. 11 is a front view of a suction and discharge valve device, and FIG. 12 is a plan view (a view taken in the direction of arrow E in FIG. 11). FIG. 13 is a plan view of a suction reed valve, and FIG. 14 is a plan view of a discharge reed valve. FIG. 15 shows a suction valve support, (A) is a front view,
(B) is a plan view. FIG. 16 shows the discharge valve support,
(A) is a front view, (B) is a plan view.

11 to 12, reference numeral 14 denotes a valve seat, which is a bolt (not shown) inserted through four bolt holes 22.
Thereby, it is fixed to the upper surface of the cylinder 10. The valve seat 14
, A suction hole 14a is pierced substantially at the center, and two discharge holes 14b are pierced on the side of the suction hole 14a.

Reference numeral 16 denotes a suction reed valve, and 17 denotes a suction valve support. The suction reed valve 16 and the suction valve support 17 are provided on the lower surface of the valve seat 14 with bolt holes 16a,
The suction reed valve 16 is fixed at its free end by a bolt 21 inserted through the suction hole 14a of the valve seat 14.
a is opened and closed from below. Reference numeral 18 denotes a discharge side reed valve, and 19 denotes a discharge valve support. The discharge side reed valve 18 and the discharge valve support 19 are inserted into bolt holes 18a and 19a with their roots on the upper surface of the valve seat 14. A discharge end 14b of the valve seat 14 is opened and closed at a free end of the discharge reed valve 18 by a bolt 20. The suction valve support 17 and the discharge valve support 1
9 is bent at a predetermined radius of curvature R, and the suction reed valve 1
When the rear surfaces of the valve 6 and the discharge reed valve 18 come into contact with the valve supports 17 and 19, the maximum lift is achieved.

The suction and discharge valve devices of such an air compressor have
The safety of the suction and discharge reed valves 16 and 18
In order to make the ratio S · F the same as in the first embodiment,
The fatigue strain ε generated at the fixed ends of the reed valves 16 and 18 is
The fatigue strain ε may be the same as that of the first embodiment.
Adjust the thickness of the reed valves 16 and 18 and the radius of the valve supports 17 and 19
Assuming the rate radius, ε = h / 2R (7) However, in the case of the first embodiment, h = 0.
Since 508 mm and R = 140 mm, ε = 0.508 / (2 × 140) = 1814 × 10^-6  Becomes

Therefore, the thickness h of the suction reed valve 16 is
0.64 mm, thickness h of the discharge reed valve 18 = 0.406
mm, the radius of curvature R of the suction valve support is 176 mm, and the radius of curvature R of the discharge valve support 19 is 112 mm. In this dimension, the suction reed valve 16 and the discharge reed valve 18
Has the same fatigue strain ε as in the first embodiment (ε = 1814
× 10 ⁻⁶ ).

[Experimental Example] The present inventors manufactured ten reed valves 16 and 18 manufactured under the above-mentioned conditions using SP700 (mill annealing) and JIS 60 type, respectively, as shown in FIG. ) And the same conditions as in the first embodiment (1200 rpm × 20 times continuous = 3.4 × 10 ⁷⁾
Times) to repeatedly perform a fatigue test. As a result, each of the above 10
No reed valves 16 and 18 were broken. Therefore, also in the reed valves 16 and 18 of this embodiment,
Similar to the first embodiment, the allowable fatigue strain: σw / E =
If a material of 3.5 × 10 ⁻³ or more is used, no fatigue fracture occurs.

The present invention is not limited to the reed valves 5a, 5b or 16, 18, but can be applied to any other thin plate-shaped valve body which is repeatedly subjected to a bending load.

[0048]

As described above, according to the present invention, according to the present invention, the material of the thin plate-shaped valve element is provided with a ratio between the fatigue strength σw and the Young's modulus E:
Using the allowable fatigue strain of σw / E = ε, and further considering the fatigue test data in a corrosive atmosphere under the condition that the safety factor against the allowable fatigue strain of the comparative material at the fatigue fracture limit of the allowable fatigue strain becomes 1 or more. Therefore, a material having sufficiently high durability in a corrosive environment can be selected as a thin plate-shaped valve body that is subjected to repeated bending loads in a corrosive environment.

According to this method, the fatigue allowable strain ε (σ
By using a material whose w / E) is 3.5 × 10 ⁻³ or more, it is possible to provide a thin plate-shaped valve having sufficiently high durability in a corrosive environment.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view (a cross-sectional view taken along line AA in FIG. 2) of a first embodiment of a suction and discharge valve device for an air compressor to which the present invention is applied;

FIG. 2 is a plan view corresponding to FIG. 1 (a view as seen from an arrow D in FIG. 1).

FIG. 3 is a longitudinal sectional view of the vicinity of a suction and discharge valve device mounting portion of the air compressor.

FIG. 4 is a plan view of a suction valve seat according to the first embodiment.

FIG. 5 is a sectional view taken along line BB of FIG. 4;

FIG. 6 is a plan view of a discharge valve seat according to the first embodiment.

FIG. 7 is a sectional view taken along line CC of FIG. 6;

FIG. 8 is a plan view of the reed valve according to the first embodiment.

FIG. 9 is a plan view of the valve support according to the first embodiment.

FIG. 10 is a plan view of the packing in the first embodiment.

FIG. 11 is a vertical cross-sectional view of a main part near a suction / discharge valve device mounting portion of an air compressor according to a second embodiment of the present invention.

FIG. 12 is a view as seen from an arrow E in FIG. 11;

FIG. 13 is a plan view of a suction reed valve according to the second embodiment.

FIG. 14 is a plan view of a discharge reed valve according to the second embodiment.

FIG. 15 is a front view (A) and a plan view (B) of a suction valve support according to the second embodiment.

FIG. 16 is a front view (A) and a plan view (B) of a discharge valve support according to the second embodiment.

FIG. 17 is a comparison chart of allowable fatigue strain and safety factor of various materials for reed valves in the first and second embodiments of the present invention.

[Description of Signs] 1 suction valve seat 1a suction hole 2 discharge valve seat 2a discharge hole 3 packing 4 parallel pin 5a reed valve (suction) 5b reed valve (discharge) 6a valve support (suction) 6b valve support (discharge) 7, 12 bolt 8 bolt hole 9 suction and discharge valve device 10 cylinder 11 cylinder lid 14a, 14b gas passage

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3H003 AA02 AC01 AD01 CC11 3H058 AA15 BB40 CA13 CA20 CB14 CB29 CD13 CD24 EE04 EE05 EE13

Claims (3)

[Claims] 1. A thin plate-shaped valve element subjected to a bending load such as a reed valve for a suction and discharge valve device of a reciprocating compressor, wherein said valve element is provided with a ratio σw / E between a fatigue strength σw and a Young's modulus E.
A thin plate-shaped valve body made of a material having a fatigue allowable strain ε defined by: ε = 3.5 × 10 ⁻³ or more. 2. The method according to claim 1, wherein the material is a titanium-based alloy.
The thin plate-shaped valve element described in the above. 3. When manufacturing a thin plate-shaped valve element subjected to a bending load, such as a reed valve for a suction and discharge valve device of a reciprocating compressor, a ratio σw between the fatigue strength σw of the material of the valve element and the Young's modulus E.
/ E = ε is defined as the allowable fatigue strain, and the ratio ε between the allowable fatigue strain ε and the allowable fatigue strain εa of the comparative material at the fatigue fracture limit.
/ Εa = S · F as a safety factor, a material having the safety factor S · F of 1 or more is selected, and the thin plate-shaped valve body is manufactured using this material. Method.