JPS61202055A - Automatic expansion valve - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to the structure of an automatic expansion valve that has both the function of reducing the pressure of high-pressure refrigerant and the function of controlling the amount of refrigerant flowing into an evaporator.

Conventional technology Conventionally, as shown in Figure 9, an automatic expansion valve installed at the refrigerant inlet of an evaporator not only acts to reduce the pressure of high-pressure refrigerant, but also controls the amount of refrigerant flowing into the evaporator. has been put into practical use (May 31, 1980, "Automotive Engineering Handbook" published by the Society of Automotive Engineers of Japan, No. 7m, p. 126).

That is, the temperature-sensitive cylinder 1 is placed in contact with the outside of the outlet side of an evaporator (not shown), and a filler is housed inside thereof. The temperature sensing cylinder 1 is communicated with the upper side of a diaphragm 3 disposed in the housing 2, and the lower side of the diaphragm 3 is communicated with the evaporator outlet side by an equal pressure t#4. The housing 2 is provided with a refrigerant inlet 5 connected to the condenser and a refrigerant outlet 6 connected to the evaporator. There is.

The diaphragm 3 is inserted into the boat 7 via a pedestal 8.
A bushing rod 9 fixed to is loosely inserted, and a spring 10 is provided at a local portion of the bushing rod 9. A ball valve 11 located on the refrigerant outlet 6 side is in contact with the lower end of the bushing rod 9, and the ball valve 11 is urged toward the bushing rod 9 by a return spring 12.

In such a structure, as shown in Figs.

A: Diaphragm 10 area - = 7.07 (lll&P1
: Filler saturated vapor pressure P, : Evaporator evaporation pressure! '8: P l-"f Ro: Radius of boat 7 = 0.13 cm R1: Radius of push rod 9 = 0.08 asl: Lift amount of push rod 9 R: Radius of ball valve 11 = 0.2 liao Fs: Return spring Initial spring force of 9 = 4 to 1: Spring constant of return spring 9 = 3.7'PIaaPa
: Inlet port 5111 pressure Pb: Outlet port 6 side pressure, now aoE f (Re''-R-) = 0.033 mm π
Defining the area as R1''=0.020m adBπR6''=0.0531m, (1) The open limit (ball valve 11 is in contact with boat 7) is PQ・A + pa-ao = pb -JL(1"'
B # and now %pa=14[p/c++t, P
If e=2Ky/at, Ps = 0.515
Kf/cIIt, Ps) 0.515 Kl
/Opens at C14 or higher.

(2) Also, when the ball valve 11 is open, Ps-A+
Pa −a□ == Pl) to al+/ + Fe
Here, the pressure P is expressed as follows using the differential force ps when the ball valve 11 starts to open completely.

P= pa −p□, PO=0.515Q/c
rIt Using this pressure P, PQ'' A = (P '' PQ) ' A ''Pk''
eLH+ k' J+ Fe -pa' aQ where P□-A = P1) -a, + Fe-Pa-a(1
Therefore, (lift amount) J=1.91F.

(3) Also, the opening area 8 formed between the ball valve 11 and the boat 7 is 1 * R6 θB '': I, where a is the opening area formed between the ball valve 11 and the inner wall 7a of the port 7 (Fig. 11). 008 R The air temperature cross-sectional area ao of port 7 is: a6=π(Re'"Rt") The opening area S to be determined is: when ao>IL, 8=a a(1(when a, B=aQ).

From the above, the 12th
The figure shows the relationship between pressure P and lift amount E, FIG. 13 shows the relationship between pressure P and opening area S, and FIG. 14 shows the relationship between lift+1tl and opening area S, respectively.

However, in the above structure, during the so-called cool-down period in which the high-temperature vehicle interior is rapidly cooled, a high heat load occurs.
The temperature of the refrigerant on the exit side of the evaporator rises, and the temperature inside the temperature sensing tube 1 rises accordingly. Therefore, the pressure P (P=P day - Pa, I"
0=0.5tsKp/cm) becomes %0.4Kp/Cd or more as shown by the solid line in FIG.

Butschrot 9 has a lift of 0.7 points.

Therefore, as shown by the solid line in Fig. 13, 1. Said riff
・The maximum opening area of 0.33 m can be obtained between the ball valve 11 and the port 7 by using the amount of 0.71 m.1. A large amount of refrigerant is introduced into the evaporator by utilizing this maximum opening area. When the interior of the vehicle is gradually cooled and the heat load is reduced, the temperature of the refrigerant on the evaporator outlet side is reduced, and the saturated vapor pressure P1 is accordingly reduced. Therefore, the pressure P decreases with the saturated steam pressure P1, and the lift amount of the bush rod 9 decreases. Therefore, the opening area is the pressure? , and can control the amount of refrigerant introduced into the evaporator according to the heat load.

Problems to be Solved by the Invention However, in the conventional device, as shown by the solid line in FIG. 14, depending on the lift amount g of the bushing rod 9,
The opening area S changes linearly.

When a certain lift amount l (0,7 m1) is exceeded, the opening area S is limited to a constant value (O, 33*), which is the maximum opening area, without increasing. For this reason, when the vehicle speed is high (approximately 604 y/h or more) during the cool-down period, the amount of superheat becomes excessive, and as shown by the dotted line in the Mollier diagram of Fig. 15, the normal cycle (solid line) On the other hand, a cycle is formed that moves to the right, and the subcool Sa obtained in the normal cycle disappears.
A refrigerant in a gas-liquid mixture flows through the boat 7 . Therefore, in the volumetric flow rate flowing within the limited opening area S, the mass flow rate inevitably decreases due to the mixing of the low-density gas refrigerant, and since the cooling amount is approximately proportional to the mass flow rate, a sufficient rapid cooling effect can be obtained. It wasn't something I could get. Therefore, as shown by the dotted line in Table 1 and Figures 13 and 14, R6 = 0.15 儂, l, = Q, IB, R =
It is also conceivable to increase the diameter of the port 7, the radius of the ball valve 11, etc. by setting 0.22 ts and ao = 0.039 cIIt, thereby increasing the maximum opening area. However, with such a means, a slight change in the lift amount l causes a large change in the opening area S, as shown as part 9 in FIG. A problem arises.

Problems to be Solved by the Invention The present invention has been made in view of the conventional situation, and includes: an actuator that expands and deforms by detecting refrigerant pressure; an actuating member that is linked to the actuator and follows the displacement; a first valve body that opens and closes in response to displacement of the operating member to control the amount of refrigerant flowing into the evaporator; death.

A second valve body is provided to control the inflow amount.

Operation In the above configuration, when a predetermined differential pressure occurs between the pressure inside the temperature sensing cylinder that detects the evaporator outlet temperature and the evaporator evaporation pressure, the actuator expands and deforms, causing the actuator to bulge and deform. The associated actuating member undergoes a corresponding displacement. Then, the first valve body opens and closes in response to the displacement of the actuating member.

Therefore, under load, the amount of refrigerant flowing into the evaporator can be precisely controlled by opening and closing the first valve body. When the differential pressure increases under high load, the actuator further expands and deforms, and the actuating member follows this. When the first valve body is fully opened by the displacement of the actuating member, the second valve body is opened and closed by a predetermined displacement or more of the first actuating member. Therefore, when cooling down during high heat load and high speed driving, by fully opening the first valve body and the second valve body,
A sufficient opening area for refrigerant inflow into the evaporator is ensured.

Therefore, a sufficient opening area increases the mass flow rate of refrigerant flowing into the evaporator, suppresses excessive superheating, and makes it possible to maximize and efficiently utilize the cooling capacity of the refrigeration cycle. .

EXAMPLE Hereinafter, an example of the present invention will be described with reference to the drawings, with the same parts and members as those of the conventional structure being denoted by the same reference numerals. That is, as shown in FIG. 1, a refrigerant inlet 5 communicating with the condenser of the refrigeration cycle and a refrigerant outlet 6 communicating with the evaporator are formed in the housing 2 so as to be perpendicular to each other.

A diaphragm 3 serving as an actuator is stretched over the upper part of the housing 2173.
Ω On the upper side is a temperature sensing tube 1 that detects the pressure of the refrigerant (Fig. 9).
A tube 1a connected to the evaporator is connected to the lower part thereof, and a pressure equalizing pipe 4 connected to the evaporator outlet side is connected to the lower part thereof.

A bushing rod 9 serving as an operating member is fixed to the center of the lower surface of the diaphragm 3 via a pedestal 8, and a projection 13 is formed near the lower end of the bushing rod 9.

The lower end of this push rod 9 protrudes toward the refrigerant outlet 6 side, and the lower end includes a first ball valve.
The valve body 14 is in contact with it. The first valve body 14 is mounted on a base 15
The bushing rod 9 is biased by the first return spring 16 via the bushing rod 9.

A tapered portion 17 is formed at the upper end of the refrigerant outlet 6, and a second valve body 19 urged by a second return spring 18 is in pressure contact with the tapered portion 17. The second valve body 19Fi has a truncated conical shape, and a boat 7 is formed in the center thereof, and the bush rod 9 is loosely inserted into the boat 7.

The contact surface of the second valve body 19 with the tapered portion 17 is finished with a centerline average roughness of 1.6 days or more, or the contact surface and the tapered portion 17 are finished with a center line average roughness of 1.6 days or more. By using pTyz (trade name: Teflon) on one side,
Refrigerant leakage is prevented.

In this embodiment having the above configuration, the balance of forces between the first valve body and the second valve body will be considered based on the values shown in FIG. In fig.

Common elements such as dimensions and signals of the first valve body 14 are the same as those of the conventional structure, and the following values are set.

Ro: Radius of the boat 7 R2: Top radius of the second valve body 19 = 0.25 cs R3: Bottom radius of the second valve body 19 = 0.5 Liaot: Height dimension of the second valve body 19 = Q, 25 ( BFs: 1st ') Initial spring force of turn spring 16 = 4Ni: i of 1st 'J turn spring 16:! 'net a=
3.75Kp / FB': Initial spring force of z2U turn spring 18 =
4.6 K Rini: Spring constant of second return spring 18 = I K
The area of y l pattern is defined as follows.

R2-”π(R2’-Ro”) a3E　π(R3'-Ro”) a, 3πu, t Under such conditions.

(11 The limit when the first valve body 14 is closed is 2 days "A"
Pa' aQ == Pb'a (1+ I'B The above relational expression is the same as that of the conventional device, and as long as this equation holds true, the first valve body 14 is in contact with the end of the boat 7. Therefore, the differential pressure Ps (=
P, -P2) exceeds the first set pressure Psetl, the bushing rod 9 descends. Therefore, the first valve body 14 resists the first return spring 16 and the boat 7
The boat 7 is released. Therefore, the refrigerant passes through the boat 7 through the inlet 5 and flows into the evaporator through the outlet 6. Therefore, the differential pressure P
8 is small, the first
By the movement of the valve body 14, the amount of refrigerant flowing into the evaporator at low load times can be closely controlled.

(2) When the second valve body 19 starts to move.

Pa-a, = Pl)-a, + Fs' The initial spring force Fs' required to bias the second valve body 19 is determined from the above equation.

Even before the projection 13 of the bushing rod 9 comes into contact with the second valve body 19, if the difference between the pressures Pa and pbO is large, a downward force acts on the second valve body 19. Therefore, only by the movement of the bushing rod 9 can the second
In order for the valve body to open, in all ranges of use,
It is necessary to set an initial spring force in the second return spring 18 such that the second valve body 19 does not open due to the pressure difference between Pa and Pl. In a normal refrigeration cycle,
The highest possible pressure is Pa = 35 Kl/Cd
Since the lowest pressure is Pb=-up/cyst, the initial spring force's is 3.84 Ky.

From now on, it is sufficient to set the initial spring force of the second return spring 18 to F's' = 4.6 K as described above. In this case, lift @1 = io,
In the case of this embodiment e. = 0.6 +u.

Then, assuming that the differential pressure FB equal to the initial spring force 9 is the second set pressure Peet2, the protrusion e13 contacts the second valve body 19 when the differential pressure P8 reaches the second set pressure Peet2, When the second set pressure Poet 2 is slightly higher than the third set pressure Pset3,
The second valve body 19 is pressed downward by the protrusion 13 . Therefore, the second valve body 19 is pushed down against the second return spring 18, and as shown in FIG.
An opening 20 is formed between the valve body 19 and the tapered portion 17.

(3) When the second valve body 19 maintains the formation of the opening 20, 6-n.

P, ・A = (P ” P6 ) ” A ” Pl
)-a ” Fa ” kJ ” Fs ” k' (1-
io)+as(Pb-Pa)-Pa-a.

Here P(1-A = Pb-a + 'F6- P,
・Since ao, P-A = kl + 6+ k'(e-
J+))+(Pl)-FB)-al Therefore, as long as the above relational expression continues, the second valve body 19 remains open.

(4) Opening area obtained by opening the second valve body 19.

As shown in FIG. 4, the tapered portion 17 and the second valve body 19
After setting the values of each part, the taper part 17 and the second valve body 19
The area of the opening formed between them is as follows.

In other words, when the second valve body 19 having a truncated cone shape is used as in this embodiment, the minimum aperture area corresponds to the 111 area M of the truncated cone in the opposite direction indicated by the dotted line in the figure, and this lateral area M is obtained from the following equation.

M = π(R2+X+R2)
cosβ) throughβ=LCOI3βexpressβh=xl co
sβ= L coc'β, so M=π(2R, P L cooβ萐β)42 CO8'
Hot fish] RofTM = π (2R, +L cos β like β
) L cos β In addition, tan PH1-R1 Using the real values shown in Table 2 for each of the above relational expressions, pressure PC""5-po) p lift t l (= 1.9 IP
).

The relationship between the opening area S (the total opening area obtained by the opening operations of the first valve body 14 and the second valve body 19) is shown in FIGS. 5 to 7 as characteristics.

Table 2 That is, according to this embodiment, the maximum opening area of the artificial structure shown by the dashed line is 0.33 cm, whereas the maximum opening area is 0.33 cm by fully opening the first valve body J4 and the second valve body 19. .56
It is possible to get a 7.

Therefore, during cool-down during high-speed running, by fully opening the first valve body 4 and the second valve body 19 as the bushing rod 9 moves downward, a large amount of refrigerant corresponding to the high load is introduced into the evaporator. This makes it possible to suppress excessive superheating and obtain excellent quenching characteristics.

In the above embodiment, the second valve body 19 is brought into surface contact with the taper s17 to obtain the fully closed state of the second valve body 19, but as shown in FIG. A hole 21 communicating with the refrigerant outlet 6 is provided, and the hole 21
It is also possible to have the second valve body 19 in line contact with the lower end edge of the valve body. According to such a structure, cutting and forming of the tapered portion 17 is not necessary, and forming and processing can be facilitated.

DETAILED DESCRIPTION OF THE INVENTION As described above, the present invention includes a first valve body that opens and closes in accordance with the displacement of an operating member linked to an actuator, and a first valve body that opens and closes in accordance with the displacement of an operating member linked to an actuator; The amount of refrigerant flowing into the evaporator is controlled by the second valve body, which opens and closes only in response to displacement.

Therefore, during steady operation of the refrigeration cycle and other small loads, only the first valve body opens and closes in response to displacement of the operating member below a predetermined value, making it possible to closely control the amount of refrigerant flowing into the evaporator. Also, when cooling down while driving at high speed,
By displacing the actuating member by a predetermined amount or more, the second
A sufficient opening area can be obtained by opening the valve body. Therefore, with a sufficient opening area, the amount of refrigerant flowing into the evaporator can be made appropriate, suppressing excessive superheating, and maximally and efficiently exerting the cooling capacity of the cold storage cycle.

In the above embodiment, the second valve body is opened after the first valve body reaches its maximum opening degree, but the second valve body can be opened and closed at any time point of the first valve body. With such a structure, it becomes possible to more freely select an appropriate opening area for a wide range of usage conditions. Furthermore, although the above-described embodiments have all shown examples having a mechanical structure, the actuator operating member may also be formed of a solenoid or the like.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing one embodiment of the present invention, and FIG. 2 is a sectional view showing an embodiment of the present invention.
3 is a sectional view showing the operating state of the embodiment, FIG. 4 is an explanatory diagram showing the main parts of the embodiment, and FIG.
6 is a pressure-opening area characteristic diagram of the same embodiment. FIG. 7 is a lift-opening area characteristic diagram of the same embodiment. 9 is a sectional view showing a conventional automatic expansion valve. FIG. 10 is a conceptual diagram of the automatic expansion valve.
Figure 1 is an explanatory diagram showing the action of the automatic expansion valve, Figure 12 is a pressure-lift characteristic diagram of the automatic expansion valve, and Figure 13 is
14 is a pressure-opening area characteristic diagram of the automatic expansion valve, and FIG. 16 is a lift amount-opening area characteristic diagram of the automatic expansion valve.
Moliel IIJ refrigeration cycle using the same automatic expansion valve
It is a diagram. 1. Temperature-sensing cylinder, 3. Aqueous unit (diaphragm)
, 4... Pressure equalization pipe, 5... Refrigerant inlet, 6... Refrigerant outlet, 7... Boat, 9... Operating member (bush rod), 13... Projection, 14... No. 1 valve body, 19.
...Second valve body. Figure 4 Figure 5 Pressure; P Kg/cm2 Figure 6 0 0.1 0.2 03 0.4 0.5 0.6
CL7 Pressure Crab PKg/cm2 Fig. 7 0 0.5 1 ・17H1:1 Fig. 10 Fig. 12, 1 Koni, Crab P Kg/cm2 Fig. 13 Pressure 7:l:P Nihiro m2

Claims (1)

[Claims] (1) An actuator that expands and deforms by detecting refrigerant pressure, an actuating member that is linked to the actuator and follows the displacement, and a first actuator that opens and closes according to the displacement of the actuating member to control the amount of refrigerant flowing into the evaporator. An automatic valve comprising: a valve body; and a second valve body that opens and closes only in response to a displacement of a predetermined amount or more of the actuating member after the first valve body is opened, and controls the inflow amount. expansion valve.