JP2002340213A - Flow control valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain stress corrosion cracking in a valve body surface. SOLUTION: A groove part 310b is arranged in a vicinal part of a welding part 310a in a valve body 310 so that an outside diametral dimension of the valve body 310 is reduced in the vicinity of the welding part 310a. Thus, when the welding part 310a of the valve body 310 is expansively contractively deformed by welding heat, restriction to expansive contractive deformation of the welding part 310a is relieved by the groove part 310b, the welding part 310a can be easily expansively contractively deformed, and the expansive contractive deformation of the welding part 310a can be absorbed by the groove part 310b. Thus, residual stress can be reduced in a part on the opposite side of the welding part 310a to the groove part 310b in the surface of the valve body 310 more than a conventional structure having no groove part 310b so that the stress corrosion cracking can be restrained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flow control valve for controlling a flow rate of a fluid, and more particularly, to a heat pump cycle (hereinafter, referred to as a supercritical heat pump) in which a refrigerant pressure on a high pressure side becomes higher than a critical pressure of the refrigerant. )).

[0002]

2. Description of the Related Art FIG. 7 is a cross-sectional view of a conventional flow control valve. This flow control valve includes a metal valve body 310 having a fluid passage 311 and a valve port 313 formed in the fluid passage 311; A valve body 314 for adjusting the opening of the mouth 313,
And a metal case 330 and the like.

The valve body 310 has a cylindrical shape extending in the vertical direction in FIG.
The case 330 is welded to a welded portion provided along the peripheral surface of the valve body 310 so that the valve body 31
4 is formed therein to form a sealed space.

[0004]

Here, the case 330
When welding to the valve body 310, the welding portion 310a
8 expands and contracts due to welding heat, whereas the inside 310d of the valve body 310 in FIG. 8 hardly deforms because the influence of welding heat is small. Therefore, a large residual stress is generated on the surface of the valve body 310 in the direction in which the valve body 310 is pulled toward the welded portion 310a by the expansion and contraction deformation in the directions indicated by arrows A1 and A2.

Further, the welded portion 3 of the valve body 310 is
In the portion near 10a, the sensitization of the metal material is promoted by the welding heat, and due to the sensitization and the above-mentioned residual stress, the surface of the valve body 310 has a stress corrosion cracking near the surface indicated by the symbol B in FIG. Is more likely to occur.

In view of the above, an object of the present invention is to suppress stress corrosion cracking on the surface of a valve body.

[0007]

In order to achieve the above object, the present invention suppresses stress corrosion cracking by reducing residual stress among sensitization and residual stress. In the present invention, a substantially cylindrical metal valve body (310) having a fluid flow path (311) through which a fluid flows and a valve port (313) formed in the fluid flow path (311), and a valve port (313). A valve body (314) for controlling the flow rate of the fluid by adjusting the opening of the valve body (3);
10) a flow rate control valve comprising a metal case (330) welded along the peripheral surface to form a sealed space for housing the valve element (314) inside on the upper surface side of the valve body (310); A small diameter portion (310b) having an outer diameter smaller than the outer diameter of the welded portion (310a) is provided near the welded portion (310a) of the valve body (310) with the case (330). And

Accordingly, the outer diameter of the portion of the valve body (310) near the welded portion (310a) is reduced by the small diameter portion (310b).
A step is formed at the part b). Therefore, as shown by an arrow A1 illustrated in FIGS. 4 and 5 described below,
When the weld (310a) of the valve body (310) expands and contracts due to welding heat, the weld (310a)
Is reduced by the step formed by the small diameter portion (310b), and the welded portion (310a) can be easily expanded and contracted.
Expansion and contraction deformation can be absorbed by the small diameter portion (310b),
The welded portion (310) of the valve body (310) is located on the opposite side of the small-diameter portion (310b) from the welded portion (310a) (the portion where stress corrosion cracking has conventionally been liable to occur).
The transmission of the expansion / contraction deformation of a) can be blocked.

Therefore, in the portion of the surface of the valve body (310) opposite to the welded portion (310a) with respect to the small diameter portion (310b), the expansion and contraction deformation due to welding heat can be suppressed, so that the residual stress is reduced. Therefore, stress corrosion cracking on the surface of the valve body (310) can be suppressed.

The shape of the small diameter portion (310b) is preferably a groove shape extending along the welded portion (310a), as in the second aspect of the present invention. Further, as in the invention according to claim 3, the valve body (310) is provided with a first cylindrical portion (310e) provided with a welded portion (310a),
The second cylindrical portion (31) having a smaller diameter than the first cylindrical portion (310e).
0f), and a portion of the second cylindrical portion (310f) adjacent to the first cylindrical portion (310e) is a small-diameter portion (3f).
It is also suitable as 10b).

Here, the flow control valve of the present invention is applied to a heat pump cycle (hereinafter referred to as a supercritical heat pump) in which the pressure of a high-pressure side refrigerant (for example, CO2 (carbon dioxide)) becomes equal to or higher than the critical pressure of the refrigerant. In this case, as compared with the case where the flow control valve of the present invention is applied to a heat pump in which the pressure of the refrigerant on the high pressure side (for example, Freon) is lower than the critical pressure of the refrigerant (hereinafter referred to as a subcritical heat pump), In order to increase the pressure resistance, it is necessary to increase the thickness of the case (330).

However, in order to weld the thick case (330), it is necessary to increase the welding energy, for example, increase the welding current in the case of arc welding, and to melt a wide range of the case (330). Because
The heat effect on the valve body (310) by the welding heat increases, the residual stress of the valve body (310) increases, and the sharpening of the metal material of the valve body (310) is greatly promoted. Therefore, in the flow control valve applied to the supercritical heat pump, the valve body (3
10) Stress corrosion cracking on the surface is particularly likely to occur.

Therefore, as in the invention according to claim 4,
The flow control valve according to any one of claims 1 to 3 is suitably applied to a supercritical heat pump cycle.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment)
A flow control valve according to the present invention is applied to a flow control valve that controls a flow rate of a refrigerant in a supercritical heat pump cycle provided in a water heater that generates hot water, and FIG. 1 shows a water heater according to the present embodiment. FIG.

In FIG. 1, a device surrounded by a chain line constitutes a supercritical heat pump. A compressor 100 sucks and compresses a refrigerant (in the present embodiment, carbon dioxide). In addition, an electric compressor in which a compression mechanism and an electric motor (drive means) for driving the compression mechanism are integrated is adopted.

Reference numeral 200 denotes a high temperature discharged from the compressor 100.
This is a hot water supply heat exchanger (gas cooler) that heats hot water by exchanging heat between high-pressure refrigerant and hot water. In the present embodiment,
By making the refrigerant flow and the hot water flow counter flow,
The heat exchange efficiency between the hot water and the refrigerant is improved.

A control valve 300 controls the flow rate of the refrigerant circulating in the heat pump cycle and the discharge pressure (high pressure side pressure) of the compressor 100 by adjusting the valve opening, and depressurizes the refrigerant. Is the control valve 30
An outdoor unit (evaporator) that evaporates low-temperature and low-pressure refrigerant depressurized at 0 and absorbs heat from the outside air (atmosphere). The details of the control valve 300 will be described later.

A refrigerant 500 is separated from a refrigerant flowing out of the outdoor unit 400 into a liquid-phase refrigerant and a gas-phase refrigerant.
This is an accumulator that allows the refrigerant to flow out to the suction side and stores excess refrigerant during the heat pump cycle.

Reference numeral 600 denotes a heat retention tank for keeping the high-temperature hot water (hot water) generated by the hot water supply heat exchanger 200 warm and stored. Reference numeral 700 denotes a pump for circulating the hot water.

Next, the control valve 300 will be described.

FIG. 2 is a sectional view of the control valve 300, and FIG.
Numeral 0 denotes a valve body having a refrigerant flow path (fluid flow path) through which the refrigerant (fluid) flows and a valve port 313 formed in the refrigerant flow path 311, and is made of a cylindrical metal (FIG. 2) extending vertically. For example, stainless steel). In the valve body 310, the refrigerant flow path 311 is connected to the upstream space 311.
a and a downstream space 311b are provided. The valve opening 313 is provided in the partition 312, and the upstream space 311a, the downstream space 311b, and the valve opening 3 are provided.
13 communicates.

Reference numeral 311P denotes an inlet pipe and an outlet pipe constituting the refrigerant flow passage 311.
10 are joined by brazing.

Reference numeral 314 denotes the opening of the valve port 313 (valve opening).
A needle valve element (hereinafter abbreviated as valve element) for adjusting the pressure
The end of the valve body 314 on the valve port 313 side is
As shown in FIG. 7, first and second tapered portions 314a and 314b whose cross-sectional area decreases toward the valve port 313 side are formed. In the present embodiment, the first tapered portion 314a is a stepped tapered portion such that the taper ratio C (see JIS B0612) is larger than the tapered ratio C of the second tapered portion 314b.

On the other hand, a first tapered portion 313a in which the opening area of the valve port 313 increases toward the valve element 314 is formed at the end of the valve port 313 on the valve element 314 side.
13 (the downstream space 311b)
A second tapered portion 313b whose opening area increases toward the downstream side is formed at an end of the second tapered portion 313b.

Incidentally, the first tapered portion 313 of the valve port 313
“a” functions as a valve seat that contacts the first tapered portion 314 a of the valve element 314 to improve the seating of the valve element 314 when the valve port 313 is closed by the valve element 314.

In FIG. 2, reference numeral 320 denotes an actuator section for moving the valve body 314 in the longitudinal direction. The actuator section 320 rotates the valve body 314 by rotating with respect to the valve body 310. 3
21, an exciting coil unit 322 for rotating the rotor unit 321 by inducing a predetermined rotating magnetic field around the rotor unit 321; a feed screw member for converting the rotational movement of the rotor unit 321 into a linear movement in the longitudinal direction of the valve body 314; 323 and the like.

Here, the rotor portion 321 comprises a substantially cylindrical sleeve 321a formed of aluminum, and a cylindrical permanent magnet (magnet) 321b adhered to the outer periphery of the sleeve 321a.

At approximately the center of the sleeve 321a, a screw portion is formed extending in the axial direction so as to screw into a screw portion formed on the outer peripheral portion of the cylindrical feed screw member 323. The member 323 is fixed to the valve body 310 by swaging. For this reason, when the rotor part 321 rotates, the rotor part 321 moves linearly in the longitudinal direction of the feed screw member 321 while rotating.

The valve element 314 is mounted on the end opposite to the first and second tapered portions 314a and 314b in a state of being disposed on the sleeve 321a so as to penetrate the sleeve 321a in the axial direction. It is suspended from the sleeve 321a so as to be locked by the retaining ring 314c.

The direction 314d is such that the contact surface pressure between the retaining ring 314c and the sleeve 321a increases (the valve element 314d).
To the valve body 313).
4 is a coil spring (elastic body) that acts on the valve element 314d when the rotor part 321 moves toward the valve port 313 while rotating.
Can be moved to the valve port 313 side by following the rotor portion 321.

The excitation coil section 322 includes first and second coils 322a and 322b, a metal yoke 322c forming a magnetic path, and a terminal section 322d for supplying a pulse current to the first and second coils 322a and 322b. 322a to 322d are molded and fixed with resin.

Incidentally, 322e is the valve body 310.
An L-shaped positioning spring having a spring characteristic and having a projection 322f fitted in the positioning hole 310c formed in the excitation coil portion 322 is formed on the exciting coil portion 322 by a P screw. Fixed.

Reference numeral 330 denotes a metal (for example, stainless steel) case which forms a predetermined magnetic gap between the rotor section 321 and the exciting coil section 322 and forms a pressure partition for accommodating the rotor section 321 side. It is formed in a cylindrical shape extending vertically in FIG. The case 330 is welded to the outer periphery of the valve body 310 by arc welding or the like. Specifically, while the entire thickness of the case 330 is melted, the outer peripheral portion of the valve body 310 is welded by melting only a surface portion of, for example, about 1 mm.

In this embodiment, since the flow rate control valve is applied to the supercritical heat pump, the structure is adapted to the high pressure of the refrigerant, and the thickness t of the case 330 is also applied to the subcritical heat pump. The thickness t (for example, 0.9 mm) is designed to be larger than that of the flow control valve to be used.

FIG. 4 shows the valve body 310 and the case 33.
FIG. 3 is a partially enlarged view of FIG.
a is a case 330 of the outer peripheral portion of the valve body 310.
And the welded portion. And the valve body 31
0 to the welded portion 310a of the outer periphery of the case 330.
On the other side (lower side in FIG. 2), a groove portion (small diameter portion) 310b extending along the welded portion 310a and having a V-shaped cross section is provided by cutting or the like.

The groove 310b is disposed near the weld 310a, and in this embodiment, the distance L1 between the weld 310a and the groove 310b is set to about 1.5 mm. Further, the groove 310b has a width L2 of about 1.5 mm.
The groove depth L3 is formed in a substantially equilateral triangular shape of about 1.3 mm. Therefore, of the outer diameters of the valve body 310, the outer diameter d2 of the groove 310b is smaller than the outer diameter d1 of the welded portion 310a by about 3.0 mm.

Incidentally, the valve body 310 of this embodiment is
Has an outer diameter dimension d1 of about φ22 mm.

Reference numerals 331 and 332 denote stoppers for restricting the maximum amount of movement when the rotor portion 321 moves to the valve body 310 side. When the stopper 332 collides, the maximum movement amount of the rotor portion 321 is regulated.

In the present embodiment, the operation of the water heater and the control valve 300 according to the embodiment will be briefly described. When the water heater is stopped, the compressor 10
0 and the pump 700, and the valve element 314
Of the first tapered portion 314a of the valve port 313
The valve port 313 is closed so as to be in close contact with 13a.

On the other hand, when hot water is generated by operating the water heater, a predetermined number of pulse currents are applied to the exciting coil section 322 to rotate the rotor section 321 by a rotation angle corresponding to the number of pulses. The valve element 314 moves in its longitudinal direction. For this reason, when the gap area (valve opening) between the second tapered portion 314 b of the valve element 314 and the valve port 313 changes, the flow rate of the refrigerant flowing through the valve port 313 changes. At this time, the valve opening degree depends on the temperature of the hot water flowing into the hot water supply heat exchanger 200 and the temperature of the hot water supply heat exchanger 2.
00 is equal to a predetermined temperature difference ΔT.
(In the present embodiment, about 10 ° C.)
4 is the first tapered portion 313 of the valve port 313.
The portion 313c of FIG.
Is controlled within a range where the valve opening is further reduced.

Here, the case 330 is connected to the valve body 31.
When welding to 0, the valve body 310
Since only the surplus portion is melted, the welding portion 310a, which is the surface portion, expands and contracts due to the welding heat, whereas the inside 310d of the valve body 310 is hardly deformed because the effect of the welding heat is small. Therefore, a large residual stress is generated on the surface of the valve body 310 in the direction of being pulled toward the welded portion 310a. Also, the valve body 310
Among them, in the vicinity of the welded portion 310a, the sensitization of the metal material is promoted by welding heat.

It is well known that sensitization in stainless steel is carried out when carbide is precipitated from a high temperature when the stainless steel is cooled from a high temperature, and the chromium concentration in a region adjacent to the precipitated carbide is reduced to reduce the grain boundary. It means that it shows corrosion susceptibility (reference material “Material Strength Science” edited by The Japan Society for Materials Science). As is well known, stress corrosion cracking is likely to occur when sensitization is promoted even with the same magnitude of residual stress, and even when sensitization is promoted to the same degree, residual stress is large. Then, stress corrosion cracking is likely to occur.

Then, as in the present embodiment, the case 330
If the wall thickness t is designed to be large, the case 330
It is necessary to increase the welding current of arc welding because the melting volume of the alloy is large. Therefore, the thermal effect of the welding heat on the valve body 310 is increased, the residual stress of the valve body 310 is increased, and the sharpening of the metal material of the valve body 310 is greatly promoted.

On the other hand, in the present embodiment, the stress corrosion cracking is suppressed by reducing the residual stress among the sensitization and the residual stress, and as described above, the portion of the valve body 310 near the welded portion 310a. Has a groove 310
b is provided, and the outer diameter of the valve body 310 is reduced.

Therefore, the welded portion 31 of the valve body 310
When the welding portion 310a expands and contracts due to welding heat, the constraint on the expansion and contraction deformation of the welded portion 310a is relaxed by the groove portion 310b, and the welded portion 310a can be easily expanded and contracted vertically in FIG. 310a
The expansion and contraction deformation of the valve body 310 can be absorbed by the groove 310b, and the weld 310
It is possible to prevent the expansion and shrinkage deformation of the welded portion 310a from being transmitted to the opposite side of a (the part where stress corrosion cracking has been liable to occur conventionally).

Accordingly, in the portion of the surface of the valve body 310 opposite to the welded portion 310a with respect to the groove 310b, expansion and contraction deformation due to welding heat can be suppressed. That is, the conventional expansion and contraction deformation (expansion and contraction deformation in the portion of the surface of the valve body 310 opposite to the welding portion 310a with respect to the groove 310b) can be reduced. Therefore, the conventional groove 3
Compared to the structure having no 10b, the welding portion 310a is formed on the groove 310b on the surface of the valve body 310.
On the other side, the residual stress can be reduced.

Incidentally, the temperature rise due to welding heat in the portion of the surface of the valve body 310 opposite to the welding portion 310a with respect to the groove 310b is substantially the same regardless of the presence or absence of the groove 310b. The degree of sensitization in the portion of the groove 310b opposite to the welded portion 310a is substantially the same regardless of the presence or absence of the groove 310b.

As described above, according to the present embodiment, the residual stress on the surface of the valve body 310 can be reduced, and the stress corrosion cracking can be suppressed.

In this embodiment, the tip of the groove 310b (the portion where the valve body 310 has the smallest diameter) is formed in a rounded shape, and this tip may be a starting point of cracking. Is to be prevented.

(Second Embodiment) In the first embodiment, the groove 310b provided on the outer peripheral portion of the valve body 310 is formed in a V-shaped cross section. In the present embodiment, as shown in FIG. 310b is formed in a rectangular shape. As described above, according to the present invention, the welded portion 310 of the valve body 310 is provided.
If the outer diameter d2 in the vicinity of a is smaller than the outer diameter d1 in the welded portion 310a, the effect of suppressing stress corrosion cracking can be obtained, and the shape of the groove 310b is V-shaped or rectangular in cross section. It is not limited to the above.

In this embodiment, the distance L4 between the weld 310a and the groove 310b is set to about 1.5 mm, the width L5 is formed to about 2.5 mm, and the groove depth L6 is set to about 1. It is formed in a substantially trapezoidal shape of 3 mm.

(Third Embodiment) In the first and second embodiments, the small diameter portion 310b of the valve body 310 is formed in a groove shape, whereas in the present embodiment, as shown in FIG. Has a two-stage cylindrical shape including a first cylindrical portion 310e provided with a welded portion 310a and a second cylindrical portion 310f having a smaller diameter than the first cylindrical portion 310e, and a boundary between the two cylindrical portions 310e and 310f. A step is provided in the portion. Therefore, the portion of the stepped portion 310b adjacent to the first columnar portion 310e in the second columnar portion 310f is a small diameter portion.

As a result, when the welded portion 310a of the valve body 310 expands and contracts due to the welding heat, the constraint on the expansion and contraction deformation of the welded portion 310a is reduced by the step portion 31.
0b, the welded portion 310a can be easily expanded and contracted in the vertical direction in FIG.
The expansion and contraction deformation of 10a can be absorbed by the stepped portion 310b, and the welded portion 310a is provided in the portion of the valve body 310 opposite to the welded portion 310a with respect to the stepped portion 310b (the portion where stress corrosion cracking has conventionally been liable to occur). The transmission of the expansion / contraction deformation of the rubber can be blocked. Therefore,
According to this embodiment, the same effects as those of the first and second embodiments can be obtained.

The outer diameter d3 of the second cylindrical portion 310f of this embodiment is formed to be about 19.5 mm.

(Other Embodiments) The groove depths L3 and L6 of the groove 310b in the first and second embodiments described above.
And the size of the step in the third embodiment is the case 3
If the thickness is equal to or more than half the thickness t of the valve body 30, the welded portion 31 is formed on the small-diameter portion 310 b of the surface of the valve body 310.
0a can suppress the expansion and contraction deformation in the part on the opposite side,
The effects of the present invention can be exhibited.

Further, the welding portion 31 in the above-described embodiment is used.
The distances L1 and L4 between Oa and the groove 310b are 3.5 mm.
If it is less than or equal to, the small diameter portion 3 of the surface of the valve body 310
The expansion and contraction deformation at the portion opposite to the welded portion 310a with respect to 10b can be suppressed, and the effects of the present invention can be exhibited.

Further, in the above-described embodiment, the heat pump control valve according to the present invention is applied to a water heater, but the present invention is not limited to this, and may be applied to, for example, an air conditioner. Can be.

Further, in the above embodiment, carbon dioxide is employed as the refrigerant, but the present invention is not limited to this, and may be, for example, ethylene, ethane, nitrogen oxide or the like. Further, the flow control valve of the present invention is not limited to application to a supercritical heat pump, but may be applied to a subcritical heat pump.

Although the valve body 310 of the first to third embodiments has a cylindrical shape, the valve body 31 of the present invention has a cylindrical shape.
Of course, 0 is not limited to a strictly cylindrical shape.

In the above-described embodiment, the operation amount of the actuator 320 is controlled by the number of pulses. However, the present invention is not limited to this, and other electric control signal values such as a current value and a voltage value are used. The actuator 320 may be controlled.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a water heater according to a first embodiment of the present invention.

FIG. 2 is a sectional view of the control valve according to the first embodiment.

FIG. 3 is an enlarged view of a throttle portion of the control valve according to the first embodiment.

FIG. 4 is a partially enlarged view of FIG. 2 showing a welded portion between the valve body and the case according to the first embodiment.

FIG. 5 is a partially enlarged view showing a welded portion between a valve body and a case according to a second embodiment of the present invention.

FIG. 6 is a sectional view of a control valve according to a third embodiment of the present invention.

FIG. 7 is a sectional view showing a conventional control valve.

FIG. 8 is a partially enlarged view of FIG. 7;

[Explanation of symbols]

Reference numeral 300: control valve, 310: valve body, 310a: welded portion, 310b: small diameter portion, 313: valve port, 314: valve body, 330: case.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Hitoshi Umezawa 7-17-24 Todoroki, Setagaya-ku, Tokyo Inside Fuji Machinery Co., Ltd. (72) Kenichi Mochizuki 7-17-24, Todoroki, Setagaya-ku, Tokyo Inside Fuji Machine Co., Ltd. (72) Inventor Yasushi Inoue 7-17-24 Todoroki, Setagaya-ku, Tokyo F-term inside Fuji Machine Co., Ltd. 3H051 AA01 BB10 CC17 EE06 FF08 3H062 AA02 AA15 BB33 CC02 DD01 GG06 HH04 HH09

Claims (4)

[Claims] 1. A fluid passage (311) through which a fluid flows and a valve port (313) formed in the fluid passage (311).
A substantially cylindrical metal valve body (310) having
A valve body (314) for controlling the flow rate of the fluid by adjusting the opening of the valve port (313); and a valve body (314) welded along a peripheral surface of the valve body (310). ) Is provided on the upper surface side of the valve body (310) and a metal case (330) that forms a sealed space for housing the inside of the valve body (310).
0) and the welded portion (3a) near the welded portion (310a).
A flow control valve provided with a small diameter portion (310b) having an outer diameter smaller than the outer diameter in 10a). 2. The flow control valve according to claim 1, wherein the small diameter portion (310b) has a groove shape extending along the welded portion (310a). 3. The valve body (310) is connected to a first cylindrical portion (310e) provided with the welding portion (310a).
And a second cylindrical portion (310f) having a diameter smaller than that of the first cylindrical portion (310e), and the first cylindrical portion (3) of the second cylindrical portion (310f).
2. The flow control valve according to claim 1, wherein a portion adjacent to 10 e) is the small diameter portion (310 b). 4. The method is applied to a heat pump cycle in which a refrigerant pressure on a high pressure side is equal to or higher than a critical pressure of the refrigerant, and controls a flow rate of the refrigerant flowing through the fluid flow path (311). The flow control valve according to any one of claims 1 to 3, wherein