JP3507616B2 - Expansion valve - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an expansion valve for adiabatically expanding a refrigerant while controlling the flow rate of the refrigerant sent to an evaporator in a refrigeration cycle.

[0002]

2. Description of the Related Art In this type of expansion valve, a temperature-sensing greenhouse in which a saturated vapor gas which is the same as or similar to a refrigerant flowing through a refrigerating cycle is sealed is arranged in an outlet side passage (low pressure refrigerant passage) of an evaporator. , A valve mechanism driven by the displacement of the diaphragm forming one wall of the greenhouse is driven, and the valve mechanism is driven by thermally expanding or contracting the saturated vapor gas in the greenhouse according to the temperature change of the low-pressure refrigerant discharged from the evaporator. By doing so, the amount of refrigerant entering the evaporator is automatically controlled.

However, if the temperature change of the refrigerant sent from the evaporator is transmitted to the temperature-sensitive chamber too quickly, small pulsation generated in the refrigerant such as a slight change in the heating degree of the refrigerant is directly transmitted to the opening / closing operation of the valve mechanism. The valve operation becomes very unstable.

Therefore, conventionally, by forming a thin vent passage for reducing the flow of the refrigerant between the low-pressure refrigerant flow path and the surface of the greenhouse, the flow rate of the low-pressure refrigerant that comes into contact with the greenhouse is reduced to reduce the low-pressure refrigerant. The valve mechanism does not respond to the small pulsation of the low-pressure refrigerant by slowing down the rate at which temperature changes are transmitted to the greenhouse (Japanese Patent Laid-Open No. 5-157405).

[0005]

However, when the amount of the refrigerant sensed by the greenhouse-sensitive side is reduced as described above, the refrigerant sensed by the greenhouse-sensitive side is detected when the flow rate of the refrigerant flowing through the low-pressure refrigerant channel is small. Becomes extremely small, so that the accuracy of the operation tends to decrease.

Therefore, the present invention can control the amount of high-pressure refrigerant sent to the evaporator by a stable operation even if the low-pressure refrigerant sent from the evaporator has a minute temperature change, and the low-pressure refrigerant It is an object of the present invention to provide an expansion valve that operates accurately regardless of the flow rate of the refrigerant.

[0007]

In order to achieve the above object, the expansion valve of the present invention has a high pressure refrigerant passage through which a high pressure refrigerant sent to an evaporator passes and a flow rate of the refrigerant passing through the high pressure refrigerant passage. A valve mechanism for changing, a low-pressure refrigerant passage through which the low-pressure refrigerant sent from the evaporator passes, and a temperature change of the low-pressure refrigerant passing through the low-pressure refrigerant passage are sensed to saturate the inside. A temperature sensitive displacement means that is displaced by thermal expansion or thermal contraction of vapor gas, and a displacement transmission member that is arranged so as to cross the low pressure refrigerant flow path and that transmits the displacement of the temperature sensitive displacement means to the valve mechanism. In the expansion valve having, a refrigerant flow restricting means for restricting the flow of the refrigerant between the low-pressure refrigerant passage and the temperature-sensing displacement means is provided, and the temperature of the low-pressure refrigerant passing through the low-pressure refrigerant passage. Through the displacement transmitting member The displacement transmitting member is formed so as to be thermally conducted to the temperature sensitive portion of the temperature sensitive displacing means, and at least a part of the displacement transmitting member is formed of a material having a low thermal conductivity to change the temperature of the low pressure refrigerant. Is delayed so as to be transmitted to the temperature sensitive portion of the temperature sensitive displacement means.

Of the displacement transmitting member, at least one of the portion in contact with the temperature-sensitive portion of the temperature-sensitive displacement means and the outer surface portion located in the low-pressure refrigerant channel has a low thermal conductivity. May be formed, and the entire displacement transmitting member may be formed of a material having a low thermal conductivity. Further, at least a part of the displacement transmitting member may be formed hollow.

Further, the refrigerant flow restricting means is a heat insulating wall made of a material having a low thermal conductivity, which is disposed between the low pressure refrigerant flow path and the temperature sensitive displacement means, and is disposed in the low pressure refrigerant flow path. A pressure equalizing through hole may be formed in the heat insulating wall to prevent a pressure difference from being generated between the surface of the temperature sensitive displacement means.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows an expansion valve 1 used in, for example, a refrigerating cycle of an automobile indoor air conditioner (car air conditioner).
0 is shown and 1 is an evaporator.

The inlet side end of the low pressure refrigerant passage 12 formed in the main body block 11 of the expansion valve 10 is connected to the outlet of the evaporator 1, and the outlet side end of the high pressure refrigerant passage 13 is the inlet of the evaporator 1. It is connected to the.

The low-pressure refrigerant flow path 12 and the high-pressure refrigerant flow path 13 are formed in parallel with each other, and a through hole 14 perpendicular to this is formed.
Penetrates between the low-pressure refrigerant channel 12 and the high-pressure refrigerant channel 13. Further, a greenhouse 30 is attached to the opening formed so as to pass outward from the low-pressure refrigerant channel 12.

The high-pressure refrigerant flow path 13 has an intermediate portion as a throttle hole 15 having a circular cross-sectional shape and a narrow cross-sectional area. The throttle hole 15 is formed coaxially with the through hole 14. There is.

The mouth of the upstream opening of the throttle hole 15 is chamfered in a taper shape with an angle of about 45 degrees to form a valve seat 20, and the diameter of the throttle hole 15 faces the valve seat 20 from the upstream side. A spherical valve body 21 having a larger diameter is arranged.

As a result, the narrowest part of the gap between the valve body 21 and the valve seat 20 becomes the throttle portion of the high pressure refrigerant flow path 13,
The high-pressure refrigerant adiabatically expands in the downstream pipeline from the evaporator 1 to the evaporator 1.

The valve body 21 is biased by the compression coil spring 17 in a direction approaching the valve seat 20 (that is, a closing direction). However, between the valve body 21 and the compression coil spring 17, one surface receives the valve body 21 and the other surface receives the compression coil spring 17 so that the biasing force of the compression coil spring 17 is transmitted to the valve body 21. The valve body receiver 16 for receiving is interposed.

Reference numeral 18 is an adjusting nut that is screwed onto the body block 11 and adjusts the urging force of the compression coil spring 17, and 19 is an O-ring for sealing between the high pressure refrigerant flow path 13 and the outside. Is.

The rod 23 inserted into the through hole 14 so as not to rattle is provided so as to be movable back and forth in the axial direction, and the lower end (the lower end face in FIG. 1) is on the head of the valve body 21. Abutting.

The rod 23 is formed thinner than the inner diameter of the throttle hole 15 so that the refrigerant can pass through the inner wall surface of the throttle hole 15, and is arranged substantially coaxially with the throttle hole 15.

Therefore, the valve body 21 is pushed by the rod 23 against the biasing force of the compression coil spring 17 to push the valve seat 2
If the distance from 0 is increased, the flow passage area of the high pressure refrigerant flow passage 13 increases. As described above, the flow passage area of the high pressure refrigerant flow passage 13 changes in accordance with the movement amount of the rod 23, and thus the amount of high pressure refrigerant supplied to the evaporator 1 changes.

The greenhouse 30 includes a housing 31 made of a thick metal plate and a diaphragm 3 made of a flexible metal thin plate.
2 (temperature sensitive displacing means), which is airtightly surrounded and faces the central portion of the lower surface of the diaphragm 32 (the surface of the greenhouse 30 when viewed from the low-pressure refrigerant channel 12 side), for example, an aluminum alloy. Made of metal diaphragm support plate 3
3 are arranged.

A gas in a saturated vapor state, which has the same or similar properties as the refrigerant flowing in the refrigerant flow paths 12 and 13, is enclosed in the greenhouse 30 and the injection hole for gas enclosure is It is closed by the stopper 34. 36 is an O-ring for sealing.

The stem 37, which is integrally formed with the diaphragm receiving plate 33, extends straight downward from the center of the lower surface of the diaphragm receiving plate 33, traverses the low pressure refrigerant flow passage 12, and the lower end surface of the rod 23. It is in contact with the end face.

Therefore, the diaphragm receiving plate 33, the stem 37, and the rod 23 serve as a displacement transmitting member for transmitting the displacement of the diaphragm 32 to the valve body 21.
Reference numeral 24 is an O-ring for sealing that is attached to the outer peripheral portion of the stem 37 in order to prevent the refrigerant from leaking from the high-pressure refrigerant channel 13 to the low-pressure refrigerant channel 12.

Diaphragm receiving plate 33 and diaphragm 3
A heat insulating plate 38a made of a plastic material having a low thermal conductivity is inserted in a contact portion with the heat insulating plate 2. Also, the stem 37
A heat insulating cylinder 38b, which is also made of a plastic material having a low thermal conductivity, is closely adhered to and covers the outer peripheral surface of the low pressure refrigerant flow passage 12 from the diaphragm receiving plate 33. Therefore, the heat insulating plate 38a and the heat insulating cylinder 38b are a part of the displacement transmitting member.

The heat insulating cylinder 38b is considerably thicker than the conventional rod (for example, having a diameter of 5) so as to have a surface area sufficient to detect the heat of the low pressure refrigerant flowing in the low pressure refrigerant passage 12.
To about 8 mm).

A heat insulating wall 40 (refrigerant flow restricting means) integrally formed with the main body block 11 and made of heat insulating plastic is provided between the space in which the diaphragm receiving plate 33 is accommodated and the low pressure refrigerant flow passage 12. It is partitioned by.

However, in the heat insulating wall 40, in addition to the hole through which the stem 37 covered with the heat insulating cylinder 38b can advance and retreat in the axial direction without resistance, the pressure in the space under the diaphragm 32 corresponds to the refrigerant pressure in the low pressure refrigerant flow passage 12. In order to be the same, a pressure-equalizing through hole 39 that communicates between them is provided.

Therefore, the low-pressure refrigerant in the low-pressure refrigerant passage 12 is located on the diaphragm receiving plate 33 side (that is, the diaphragm 3).
The temperature of the low-pressure refrigerant flow path 12 is transmitted to the lower surface of the diaphragm 32 by heat conduction from the heat insulating cylinder 38b through the stem 37, the diaphragm receiving plate 33 and the heat insulating plate 38a. To be done.

In the expansion valve 10 thus constructed, when the temperature of the low-pressure refrigerant flowing in the low-pressure refrigerant passage 12 is lowered, the temperature of the diaphragm 32 is lowered and the temperature-sensing greenhouse 30 is reduced.
The saturated vapor gas therein condenses on the inner surface of the diaphragm 32.

Then, the pressure in the greenhouse 30 is lowered and the diaphragm 32 is displaced to the inside of the greenhouse 30, and accordingly, the diaphragm receiving plate 33 and the stem 37 are moved to the rod 2.
Since the rod 23 is displaced in the axial direction of 3 in a direction away from the rod 23, the rod 23 is pushed by the compression coil spring 17 to move. As a result, the valve body 21 moves to the valve seat 20 side and the flow passage area of the high-pressure refrigerant is narrowed, so that the flow rate of the refrigerant sent to the evaporator 1 is reduced.

When the temperature of the low-pressure refrigerant flowing in the low-pressure refrigerant passage 12 rises, the valve body 21 is pushed by the rod 23 and separated from the valve seat 20 by the operation reverse to the above, and the passage area of the high-pressure refrigerant widens. The flow rate of high-pressure refrigerant sent to the evaporator 1 increases.

In this way, the valve body 21 is moved to the valve seat 20 through the operations of the greenhouse 30 and the diaphragm receiving plate 33, the stem 37, the rod 23, etc. in accordance with the temperature of the low-pressure refrigerant sent from the evaporator 1. The amount of high-pressure refrigerant sent to the evaporator 1 is controlled by being opened and closed with respect to.

In such operation, the low pressure refrigerant flow path 1
When the temperature change of the low-pressure refrigerant flowing inside 2 is transmitted to the greenhouse 30, the heat insulating plate 38a and the heat insulating cylinder 38 having low thermal conductivity
It takes time for heat conduction in b.

Therefore, the diaphragm 32 and the valve body 21 that follows it operate at a very slow response speed to the temperature change of the low-pressure refrigerant flowing in the low-pressure refrigerant channel 12, and the fine pressure of the low-pressure refrigerant is small. It does not react to changes in temperature.

Further, since the heat insulating cylinder 38b can have a surface area sufficient to come into contact with the low pressure refrigerant flowing in the low pressure refrigerant flow passage 12 to detect its temperature, even if the flow rate of the low pressure refrigerant is small, The temperature is accurately transmitted to the greenhouse 30 side, and the valve body 21 is correctly controlled to open and close with respect to the valve seat 20.

The area and thickness of the heat insulating plate 38a and the heat insulating cylinder 38b may be appropriately selected according to design specifications and the like, and only one of the heat insulating plate 38a and the heat insulating cylinder 38b may be provided. .

Further, the entire stem 37 (or the stem 37
The entire diaphragm receiving plate 33) may be formed of a plastic material having a low thermal conductivity. Further, as shown in FIG. 2, a part of the stem 37 formed of a plastic material having a low thermal conductivity may be formed hollow.

[0039]

According to the present invention, at least a part of the displacement transmitting member for transmitting the temperature change of the low-pressure refrigerant passing through the low-pressure refrigerant passage to the temperature-sensing portion of the temperature-sensing displacement means by heat conduction has low thermal conductivity. By forming it with a material so as to delay the time required for the temperature change of the low-pressure refrigerant to be transmitted to the temperature-sensing portion of the temperature-sensing displacement means, a small temperature change can be made in the low-pressure refrigerant sent from the evaporator. However, the amount of high-pressure refrigerant sent to the evaporator can be controlled by stable operation, and the displacement transmission member must have a thickness that has a surface area sufficient to sense the temperature of the low-pressure refrigerant. Therefore, even if the flow rate of the low-pressure refrigerant is small, the valve operation can be accurately performed.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of an expansion valve according to an embodiment of the present invention.

FIG. 2 is a partial sectional view of a second embodiment of the present invention.

[Explanation of symbols]

1 evaporator 10 Expansion valve 12 Low pressure refrigerant flow path 20 seat 21 valve 30 feeling greenhouse 32 Daifuramu 33 Diaphragm receiving plate 37 stem 38a heat insulating plate 38b heat insulation tube 39 Pressure equalizing hole 40 insulation wall

Claims (4)

(57) [Claims] 1. A high-pressure refrigerant passage through which a high-pressure refrigerant sent to an evaporator passes, a valve mechanism for changing the flow rate of the refrigerant passing through the high-pressure refrigerant passage, and a low-pressure refrigerant sent out from the evaporator. A low-pressure refrigerant flow path that passes through, a temperature-sensitive displacement means that senses a temperature change of the low-pressure refrigerant that passes through the low-pressure refrigerant flow path, and displaces the saturated vapor gas enclosed therein by thermal expansion or thermal contraction, An expansion valve having a displacement transmitting member arranged to traverse the low-pressure refrigerant passage and transmitting a displacement of the temperature-sensitive displacement means to the valve mechanism, wherein the low-pressure refrigerant passage and the temperature-sensitive displacement means A refrigerant flow restricting means for restricting the flow of the refrigerant between is provided, and the temperature of the low-pressure refrigerant passing through the low-pressure refrigerant channel is transferred to the temperature-sensing portion of the temperature-sensing displacement means via the displacement transmitting member. The above-mentioned displacement transmission To form a member, of the displacement transmission member, the temperature sensing portion of said temperature sensitive displacement means
Form the contact part with a material with low thermal conductivity,
An expansion valve characterized by delaying the time required for the temperature change of the low-pressure refrigerant to be transmitted to the temperature sensing portion of the temperature sensing displacement means. 2. The expansion valve according to claim 1, wherein the entire displacement transmitting member is formed of a material having a low thermal conductivity. 3. At least a part of the displacement transmitting member,
The expansion valve according to claim 1 or 2, which is hollow. 4. The refrigerant flow restricting means is an adiabatic wall made of a material having a low thermal conductivity, which is disposed between the low pressure refrigerant flow path and the temperature sensitive displacement means, and is disposed in the low pressure refrigerant flow path. 4. The expansion valve according to claim 1, 2 or 3, wherein a pressure equalizing through hole is formed in the heat insulating wall for preventing a pressure difference from being generated between the surface portion of the temperature sensitive displacement means.