JPH0621746B2 - Expansion valve - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an expansion valve incorporated in a cooling cycle of an automobile air conditioner or the like.

(Prior Art) A cooling cycle of an automobile air conditioner is shown in FIG. 3, and the cooling cycle 1 is a compressor 3 driven by a running engine (not shown) via a clutch 2.
And a condenser 4 for cooling and condensing the high temperature and high pressure gas refrigerant by the compressor 3, and a liquid tank 5 for separating gas and liquid of the refrigerant condensed here and removing water and dust in the refrigerant. An expansion valve 6 for expanding the refrigerant from the liquid tank 5 and an evaporator 7 for exchanging heat between the air and the refrigerant for cooling the air blown into the vehicle compartment are connected by a pipe 8. There is. The flow of the refrigerant in the cooling cycle 1 is shown in the Mollier diagram as shown in FIG. In FIG. 4, symbol L indicates a saturated liquid line, symbol V indicates a saturated vapor line, and symbols A to
D indicates a position corresponding to the symbols A to D shown in FIG. 3 during the cooling cycle. As shown in FIG. 4, the gas refrigerant (A position) that is adiabatically compressed by the compressor 3 and becomes high temperature and high pressure releases heat to the outside by the condenser 4 to become a low temperature and high pressure liquid refrigerant (B position). . Next, this liquid refrigerant passes through the expansion valve 6 and is squeezed and expanded there to become a mist-like refrigerant (position C). The atomized refrigerant enters the evaporator 7, absorbs heat from the outside, evaporates and evaporates, and serves to cool the air, and then is sucked into the compressor 3 at the position D.

If the refrigerant sucked into the compressor 3 contains a liquid refrigerant, the compressor 3 will perform liquid compression. Therefore, the compressor 3 has a predetermined refrigerant superheat degree indicated by SH in FIG. The refrigerant having the heat amount is sucked.

The expansion valve 6 used in such a cooling cycle 1 is for expanding the refrigerant while automatically adjusting the refrigerant flow rate that matches the required cooling capacity according to the fluctuation of the thermal load of the evaporator 7. Yes, in the past, actual development Sho 58-175272
There is one shown in the publication. An example of such a conventional expansion valve 6 is shown in FIG. An inlet side flow passage 11 and an outlet side flow passage 12 are formed in the casing 10, and a valve body 14 for opening and closing the throat portion 13 connecting the inlet side flow passage 11 and the outlet side flow passage 12 is mounted. Has been done. The inlet side flow passage 11 is connected to the condenser 4 shown in FIG. 3 via a liquid tank 5 by piping, and the outlet side flow passage 12 is connected to the evaporator 7 by piping.

A pressure equalizing case 15 is attached to the casing 10, and a pressure chamber 17 is formed outside a diaphragm 16 provided in the pressure equalizing case 15. This pressure chamber 17 is connected to a temperature-sensitive cylinder 18 which is attached to the outlet side of the evaporator 7 and has a refrigerant sealed therein. Due to a change in pressure in the pressure chamber 17 due to a temperature change of the refrigerant in the temperature-sensitive cylinder 18, The diaphragm 16 is adapted to operate. The diaphragm 16 is connected to the valve body 14 by an operating rod 19.
A coil spring 22 is provided between the retainer 20 that comes into contact with the valve body 14 and the spring retainer 21 that is screwed into the outlet-side flow passage 12, and the throat portion 13 is attached to the valve body 14 by the spring coil 22. Elasticity in the closing direction is added. The expansion valve 6 shown in FIG. 5 is of a type called an internal pressure equalization type expansion valve, and a communication hole 23 formed in the casing 10 allows the inside of the diaphragm 16 and the outlet side flow passage 1 to be formed.
It is in communication with 2.

The opening degree of the valve body 14 is a force acting in the direction of opening the valve body 14 due to the pressure of the gas in the pressure chamber 17, the pressure of the refrigerant acting inside the diaphragm 16 through the communication hole 23, and the coil spring 22. It is determined by the balance with the force acting in the closing direction of the valve body 14 due to the elastic force of the refrigerant, and the refrigerant having a flow rate according to the opening thereof flows into the evaporator 7.

The expansion valve used in the cooling cycle 1 is the sixth conventional valve.
There is an external pressure equalization expansion valve 6 as shown. This expansion valve 6
Is almost the same as the structure of the internal pressure-equalizing expansion valve 6 shown in FIG. 5, except that the pressure of the refrigerant at the outlet of the evaporator 7 is supplied to the inside of the diaphragm 16 by the tube 24. In FIG. 6, members common to those shown in FIG. 5 are designated by the same reference numerals.

(Problems to be Solved by the Invention) When the cooling cycle 1 shown in FIG. 3 is stopped, the valve element 14 of the expansion valve 6 shown in FIGS. And the pressure acting on the inside of the diaphragm 16 closes the throat portion 13. When the compressor 3 is driven from this state, the pressure inside the evaporator 7 decreases, the pressure inside the diaphragm 16 decreases, and the pressure in the pressure chamber 17 causes the force that opens the valve body 14 via the diaphragm 16 to be the coil. It becomes larger than the elastic force of the spring 22, and the valve body 14 is opened. This allows
Refrigerant will be supplied into the evaporator 7. As described above, the elastic force of the coil spring 22, that is, the spring force, is not only the characteristic of the gas in the temperature sensitive cylinder 18 and the saturated pressure characteristic of the refrigerant, but also the valve opening of the expansion valve 6 that causes the valve body 14 to open and close. This will greatly affect the degree characteristics.

Therefore, comparing the case where the elastic force of the coil spring 22 is made strong and the case where the elastic force of the coil spring 22 is made weak under the same conditions of the gas characteristics and the like in the temperature sensitive cylinder 18, an expansion valve using the coil spring 22 having a strong elastic force. In No. 6, since the pressure in the evaporator 7 becomes lower when the valve body 14 opens after the compressor 3 is activated and the refrigerant starts flowing into the evaporator 7, cooling is started at the beginning of the start of the cooling cycle 1. The time characteristic from the start to the predetermined cooling state, that is, the cool down characteristic is improved. Then, in the expansion valve 6 using the coil spring 22 having an elastic force weaker than this, the evaporator 7 when it begins to flow into the evaporator 7
Since the internal pressure becomes higher, the temperature of the evaporator 7 becomes higher than in the case where the elastic force is strong due to the relationship between the evaporation pressure of the refrigerant and the temperature. Therefore, the cooling performance at the initial stage of start-up, that is, the cool-down characteristic is deteriorated.

As described above, in order to improve the cool-down characteristic in the initial stage of starting, the coil spring 22 having a strong elastic force may be used. However, when the elastic force is increased, the cooling cycle is in a steady state, especially under the hot sun. When the heat load on the evaporator 7 is large, such as when the vehicle is traveling in, the amount of refrigerant sufficient to cool the passenger compartment is not supplied to the inside of the evaporator 7. Therefore, at this time, the superheat degree of the refrigerant sucked into the compressor 3 becomes high and the superheat amount S
H increases to, for example, about 10 to 15 degrees.

Therefore, by making the elastic force of the coil spring 22 weaker and allowing a desired amount of refrigerant to flow in the evaporator 7 in the steady state, the refrigerant in the evaporator 7 when the valve body 14 of the expansion valve 6 starts to open. Since the pressure becomes higher, a sufficient cooling performance can be obtained by a large amount of refrigerant when the cooling cycle 1 is operated for a relatively long time, whereas the cooling performance at the initial start-up of the cooling cycle 1, that is, This means that the cooldown characteristics are not good. Therefore, in the case of this characteristic, the compressor 3
Since a larger amount of refrigerant is sucked in, the degree of superheat of the refrigerant becomes lower than that in the case described above, and the superheat amount SH at this time is, for example, about 5 degrees.

From the viewpoint described above, conventionally, the opening characteristic of the valve body 14 of the expansion valve 6 is set according to the heat load in a steady traveling state, so that there is a problem that the cooldown characteristic at the initial stage of starting is not good. .

The present invention has been made in view of the above-mentioned problems of the prior art, and an object thereof is to maintain a desired cooling performance even in a steady state and to improve a cool-down characteristic in an initial stage of starting a cooling cycle.

(Means for Solving the Problems) The present invention for achieving the above-mentioned object is provided in a throat portion in which a valve seat is formed by connecting an inlet side flow passage and an outlet side flow passage formed respectively in a casing. A valve body for opening and closing is installed, and the diaphragm in the pressure equalizing case attached to the casing and the valve body are interlocked by a valve actuating rod to adjust the opening of the throat part by the diaphragm. In the valve, a coil spring that applies an elastic force to the valve body in a direction to close the throat portion is provided between the valve body and a piston that is axially slidably mounted in the casing. Forming a fluid guide path in the casing for connecting the inlet-side passage and the piston and supplying a fluid pressure for advancing toward the coil spring with respect to the piston, and mounting the fluid guide path in the casing The expansion valve is provided with a pilot valve that opens and closes the fluid guide path by an electromagnet actuator.

(Operation) When the high-pressure liquid refrigerant reaching the inlet-side flow passage slides the piston from the fluid guide passage through the pilot valve when the electromagnet is energized, the coil spring contracts and the valve body closes the throat portion. The elastic force exerted by the coil spring in the direction increases. As a result, the cooling performance at the initial stage of starting the cooling cycle, that is, the cool-down characteristic is improved. Then, in a steady state after the lapse of a predetermined time, the fluid guide passage is blocked by the operation of the electromagnet, the piston slides in the direction opposite to the above, and the coil spring expands. As a result, a larger amount of the refrigerant passes through the throat portion and a desired cooling performance in a steady state can be obtained.

(Embodiment) Next, an expansion valve according to an embodiment of the present invention shown in FIGS. In FIGS. 1 and 2, the same members as those of the conventional expansion valve described above are designated by the same reference numerals.

In the casing 10, an inlet side flow passage 11 and an outlet side flow passage 12 are provided.
And a valve body 14 for opening and closing the throat portion 13 connecting the inlet side flow passage 11 and the outlet side flow passage 12 are mounted. The inlet side flow passage 11 is connected to the condenser 4 shown in FIG. 3 via a liquid tank 5 by piping, and the outlet side flow passage 12 is connected to the evaporator 7 by pipes.
Connected to.

A pressure equalizing case 15 is attached to the casing 10, and a pressure chamber 17 is formed outside a diaphragm 16 provided in the pressure equalizing case 15. This pressure chamber 17 is connected to a temperature-sensitive cylinder 18 which is attached to the outlet side of the evaporator 7 and has a refrigerant sealed therein. Due to a change in pressure in the pressure chamber 17 due to a temperature change of the refrigerant in the temperature-sensitive cylinder 18, The diaphragm 16 is adapted to operate. A spacer 26 integral with the diaphragm 16 is in contact with one end of an operating rod 19 provided slidably in the casing 10 in the axial direction, and the other end of the operating rod 19 is in contact with a retainer 20 supporting the valve element 14. The diaphragm 16 and the valve body 14 are in contact with each other. A plurality of operating rods 19 are provided.

In the casing 10, the outlet side flow passage 12 and the throat portion 1 are provided.
3, a cylindrical expansion chamber 27 is formed between
The valve body 14 is located in the expansion chamber 27. Further, a piston 30 is axially slidably mounted in the casing 10 along the inner peripheral surface of the expansion chamber 27, and a coil spring 22 is provided between the piston 30 and the retainer 20. The coil spring 22 gives an elastic force to the valve body 14 in a direction of closing the throat portion 13. A radial end surface 32 that abuts a large-diameter portion 31 formed on the piston 30 is formed on the casing 10 in order to regulate the most forward movement position of the piston 30 toward the valve body 14.

Cylindrical support fitting 33 integrated with the casing 10
The pilot housing 34 is screwed to the piston housing 34, and the rear end surface of the piston 30 is brought into contact with the tip end surface of the pilot housing 34, whereby the backward limit position of the piston 30 is restricted.

A through hole 35 is formed in the radial wall portion located at the tip of the pilot housing 34, and a through hole 36 communicating with the through hole 35 is formed in the peripheral wall portion. Further, the casing 10 is formed with a through hole 37 having one end communicating with the inlet side flow passage 11 and the other end communicating with the through hole 36. These through holes 35, 36, 37 are provided in the inlet side flow passage. A fluid guide path 3 that connects 11 and the piston 30 and supplies a fluid pressure to the piston 30 in a direction of advancing toward the coil spring 22.
Make up eight.

An electromagnet 39 is integrated with the pilot housing 34, and a valve chamber 40 formed in the pilot housing 34 is provided with a pilot valve 41 that opens and closes the through hole 35 to open and close the fluid guide path 38. The pilot valve 41 is fixed to an actuator 42 that reciprocates by an electromagnet 39. A coil spring 44 is provided between the plug 43 integrated with the housing 34 and the actuator 42, and when the electromagnet 39 is not energized, the pilot valve 41 penetrates by the elastic force of the coil spring 44. The hole 35 is closed.
Therefore, when the electromagnet 39 is energized, the coil spring 44
The actuator 42 is actuated against the elastic force of, the pilot valve 41 opens the through hole 35, and the refrigerant in the inlet side flow passage 11 is supplied to the piston 30 through the fluid guide passage 38.

A fluid chamber 45 into which the fluid from the inlet-side flow passage 11 enters is formed in the piston 30, and a radial wall at the tip of the piston 30 has a pore 46 for allowing the fluid in the fluid chamber 45 to escape. . In FIG. 1, reference numeral 47 indicates an O-ring for sealing, and reference numeral 48 indicates a lead wire for supplying a current to the electromagnet 39. The expansion valve shown in FIG. 1 is an external pressure equalization type expansion valve, and the pressure of the refrigerant at the outlet of the evaporator is supplied to the inside of the diaphragm 16 by the tube 24.

The electric circuit for controlling the energization of the electromagnet 39 is shown below.
As shown in the figure, the thermistor 50 attached to the evaporator 7 is connected to the amplifier 51, and the amplifier 51 detects the resistance value corresponding to the temperature of the outer surface of the evaporator 7 detected by the thermistor 50, and the Energization is controlled. For example, when the temperature of the outer surface of the evaporator 7 is 5 ° C. or higher, the electromagnet is set to be energized.

Next, the operation will be described. When the cooling cycle 1 is stopped, the valve element 14 closes the throat portion 13 by the elastic force of the coil spring 22. When the compressor 3 is driven under this condition to start the operation of the cooling cycle 1, if the temperature of the outer surface of the evaporator 7 is equal to or higher than the set temperature such as 5 ° C. at that time, the electromagnet 39 is energized. As a result, the pilot valve 41 opens the fluid guide passage 38, so that the refrigerant from the inlet-side passage 11 is supplied into the fluid chamber 45. As a result, the piston 30 advances toward the valve body 14 and contracts the coil spring 22 until the large-diameter portion 31 contacts the radial end surface 32, and the valve body 14 has a strong elastic force by the coil spring 22. Will be added in the direction of closing the throat portion 13. Therefore, the valve body 14 opens the throat portion 13 and causes the refrigerant to flow into the evaporator 7 when the pressure inside the evaporator 7 is relatively low, and even if a small amount of the refrigerant reaches a desired temperature. Thus, the evaporator 7 can be cooled rapidly. At this time, it is possible to set the superheat amount to about 10 to 15 degrees. This improves the cooldown characteristics.

When a predetermined time has elapsed from the above-mentioned state and a steady cooling operation state is reached, the temperature of the evaporator 7 falls below a predetermined temperature. Then, the thermistor 50 detects this, and the energization of the electromagnet 39 is released, and the pilot valve 41 closes the through hole 35 by the elastic force of the coil spring 44 and closes the fluid guide path 38.
In addition, the refrigerant in the fluid chamber 45 is discharged from the pores 46 through the outlet-side flow passage 1
It leaks to 2. When the fluid guide passage 38 is closed, the piston 30
The fluid pressure does not act on, and the vehicle retreats to the position shown by the solid line in FIG. Thereby, the elastic force applied by the coil spring 22 to the valve body 14 in the direction of closing the throat portion 13 becomes weaker than in the case described above, and a larger amount of the refrigerant flows into the evaporator 7. Since a large amount of refrigerant is supplied to the evaporator 7 in this way, it is possible to cool the evaporator 7 sufficiently following the heat load in the steady state. The superheat amount in this steady state is about 5 degrees.

Compared to the total operation time of the cooling cycle 1 shown in FIG. 3, the electric magnet 39 is energized in an early stage of cooling, which is extremely short.
It is for operating the
Very little power is consumed to activate the electromagnet 39. In the embodiment of the present invention shown in FIG. 1, the external pressure equalization type expansion valve is shown, but it goes without saying that the present invention can also be applied to the internal pressure equalization type expansion valve.

(Effects of the Invention) As described above, according to the expansion valve of the present invention, it is possible to change the elastic force of the coil spring for imparting the elastic force to the valve body in the closing direction. Therefore, it is possible to improve the cool-down characteristic by adding a strong resilience to the valve body in the initial stage of the cooling operation. Further, when in a steady state, it is possible to supply a large amount of refrigerant into the evaporator with a weak elastic force and perform sufficient cooling. As a result, there is an effect that excellent cooling performance can be maintained in the initial and steady states of the cooling operation. Moreover, the refrigerant in the cooling cycle is used to expand and contract the coil spring to change the elastic force of the coil spring, and the power consumption of the electromagnet for supplying or stopping the supply of the refrigerant is extremely small. There is an effect.

[Brief description of drawings]

FIG. 1 is a sectional view showing an expansion valve according to an embodiment of the present invention,
2 is an electric circuit diagram for controlling energization of the electromagnet in FIG. 1, FIG. 3 is a refrigerant circuit diagram showing a general automobile cooling cycle, and FIG. 4 is a cooling cycle shown in FIG. 5 and 6 are sectional views showing a conventional expansion valve. 6 ... Expansion valve, 7 ... Evaporator, 10 ... Casing, 11 ... Inlet side flow passage, 12 ... Outlet side flow passage, 13 ...
… Throat part, 14 …… Valve body, 15 …… Pressure equalizing case, 1
6 ... Diaphragm, 17 ... Pressure chamber, 18 ... Temperature sensing cylinder, 19 ... Actuating rod, 30 ... Piston, 38 ... Fluid guide path, 39 ... Electromagnet, 41 ... Pilot valve, 42
...... Actuator,

Front Page Continuation (72) Inventor Ryoichi Kubo 8 Sakaemachi, Sano City, Tochigi Prefecture Japan Radiator Co., Ltd. Sano factory (72) Inventor Isao Sendo 1211-4, Kasudacho, Hachioji, Tokyo (56) References 54-99160 (JP, U)

Claims (1)

[Claims] 1. A valve body for connecting an inlet-side flow passage and an outlet-side flow passage formed in a casing and opening and closing the same to a throat portion having a valve seat formed therein, and mounted on the casing. In an expansion valve in which a diaphragm in the pressure case and the valve body are interlocked by a valve operating rod to adjust the opening of the throat portion by the diaphragm,
A coil spring is provided between the piston, which is slidably mounted in the casing in the axial direction, and the valve body, and a coil spring that applies an elastic force to the valve body in a direction of closing the throat portion is provided. A fluid guide path for connecting a side flow path and the piston to supply a fluid pressure for advancing toward the coil spring to the piston is formed in the casing, and the fluid guide is provided by an electromagnet actuator attached to the casing. An expansion valve having a pilot valve for opening and closing a passage.