JP2645854B2 - Two-stage expansion valve - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an expansion valve used in a heat pump type air conditioner or the like.

[Conventional technology]

In the heat pump type cooling / heating device, the switching of the cooling / heating is performed by reversing the flow direction of the refrigerant. However, when the outdoor temperature is low during heating, frost may be formed on the outdoor heat exchanger. Conventionally, as a defrosting method in such a case, a method of switching the flowing direction of the refrigerant by a four-way valve and supplying a high-pressure and high-temperature refrigerant to the outdoor heat exchanger has been often used. However, in this method, the indoor heat exchanger becomes an evaporator, which is inconvenient.Therefore, even during defrosting, the high-temperature refrigerant is supplied to the indoor heat exchanger without changing the flow direction of the refrigerant, and the high temperature is applied to the outdoor heat exchanger. A method for supplying a refrigerant has been proposed.

With respect to such methods, be introduced before the outdoor heat exchanger A to a part of the high-temperature high-pressure refrigerant on the discharge side of the compressor C as Figure 8 directly through the bypass pipe with the solenoid valve S ₁ and the like Or
There are means such as introducing the warm coolant remains incomplete condensation of the indoor heat exchanger B to the outdoor heat exchanger A or via a ninth solenoid valve S ₂ were parallel in the expansion valve E as drawing, etc. Was.

However, all of these means require additional pipes, solenoid valves, and the like, and the control circuit becomes complicated, so that an increase in maintenance costs cannot be avoided.

[Problems to be solved by the invention]

Therefore, the present invention seeks to provide a compact expansion valve having both functions of a conventional expansion valve and a solenoid valve and capable of defrosting an outdoor heat exchanger without adding a special pipe or the like. Things.

[Means for solving the problem]

In order to achieve the above object, the two-stage expansion valve of the present invention has a first expansion valve that can block only the passage of fluid from the first fluid passage.
An on-off valve and a back pressure-operated pilot-type second on-off valve capable of preventing only the passage of fluid from the second fluid passage are sequentially connected in series and provided between the first fluid passage and the second fluid passage, and a flow rate is controlled. A bidirectional expansion valve that can be continuously controlled is provided between the first fluid passage and the back pressure space of the second on-off valve, and a fixed throttle passage having a flow resistance greater than a flow resistance when the expansion valve is fully opened. Communicating between the back pressure space and the second fluid passage,
More specifically, a control valve seat provided on a partition wall that separates an upper valve chamber communicating with the first fluid passage and a lower valve chamber communicating with the second fluid passage. An expansion valve is provided with a needle valve body that advances and retreats from the upper valve chamber side in a stepless manner, and a piston-like spring biased toward a second valve seat communicating with the first fluid passage is formed in the lower valve chamber. A fixed throttle flow that fits the second valve body slidably up and down to form a back pressure space between the partition and the second valve body and connects the lower valve chamber and the back pressure space. A passage having a flow resistance greater than a flow resistance when the needle valve is fully opened, forming a first valve seat on the first fluid passage side of the second valve seat, and It is preferable to provide a two-stage expansion valve of the present invention by providing a first valve body that can prevent the inflow of fluid from the first fluid passage.

In addition, it is preferable that the advance and retreat of the needle valve element in the valve of the present invention be performed steplessly by incorporating a pulse motor or the like.

Further, the fixed throttle passage connecting the lower valve chamber and the back pressure space may be provided, for example, through the second valve body, or may be provided on the valve body side, or may be provided on the valve body side. It may be provided as a gap with the lower valve chamber side wall. The flow resistance of the fixed throttle flow path is greater than the flow resistance of the needle valve when the needle valve is fully opened. Therefore, when the needle valve is fully opened, the pressure in the back pressure space becomes almost equal to the pressure in the upper valve chamber and thus the first fluid passage. It is desirable to be constituted as follows.

In the two-stage expansion valve of the present invention, a relief passage is provided in the second valve body for connecting the back pressure space and the first valve seat opening, and the relief passage extends from the first fluid passage to the back pressure space. By providing the relief valve that allows only the flow of the fluid, the closed state of the first valve when the fluid flows from the first fluid passage to the second fluid passage can be stably maintained, and the relief can be performed. The valve body is provided with an operating rod penetrating the relief passage, and the tip of the operating rod is formed at a position where the operating rod is pushed up by the first valve element when the first valve element closes the first valve seat. It will work more reliably.

(Operation)

The two-stage expansion valve of the present invention configured as described above has a
When the fluid flows in from the fluid passage, the lower valve chamber becomes high pressure, and when the expansion valve is closed, the lower valve chamber and the back pressure space are equalized through a fixed throttle flow path, so that the lower valve chamber is closed by a spring. The second on-off valve is more strongly closed by the fluid pressure. Next, when the expansion valve is gradually opened from this state, the fluid enters the upper valve chamber via the back pressure space, and flows toward the first fluid passage.

Further, when the expansion valve is opened, the flow rate increases, but when the expansion valve is almost fully opened, the pressure in the back pressure space is greatly reduced, and the second valve body is pushed up while compressing the spring by the fluid pressure in the lower valve chamber. Is opened.

On the other hand, when the fluid flows from the first fluid passage, the first on-off valve is closed to prevent the fluid from flowing into the lower valve chamber. However, since the fluid can flow into the upper valve chamber, the fluid flows toward the second fluid passage by the expansion valve. The flow rate will be controlled.

Embodiment 1 FIG. 1 shows an example of a two-stage expansion valve of the present invention.

Reference numeral 1 denotes a valve main body, on which an upper lid 1a is mounted, and an upper valve chamber 2a is formed between the partition 2 mounted inside and the upper lid 1a. The partition 2 is provided with a control valve seat 2 b, which is opened and closed by a needle valve 3 driven by an actuator 9.

Reference numeral 9 denotes an electric actuator mounted on the upper part of the valve body 1. Reference numeral 9a denotes a male screw cylinder that is erected on the upper lid 1a so that the needle valve body 3 can pass therethrough, and 9b denotes a rotor that is rotatably screwed to the male screw cylinder 9a. 9c is a stator coil mounted outside the shield tube 9b. The rotor 9b and the upper end 3a of the needle valve body 3 are rotatably connected. The rotor 9b causes axial movement along the male screw cylinder 9a as it rotates, and this axial movement is performed by a spring 9e. The play is transmitted to the needle valve body 3 without play, and the needle valve body 3 moves forward and backward in proportion to the rotation amount of the rotor 9b.

A second fluid passage 4 is opened on the side wall of the lower valve chamber 1b in the valve body 1, and a second valve seat 1c is formed on the upper surface of the bottom wall. A first valve seat 1d is formed on the lower surface of the bottom wall, and a communication passage is provided between the first on-off valve chamber 1e and the upper valve chamber 2a below the first valve seat 1d.
1f is provided. The first opening / closing valve chamber 1e communicates with the first body passage 5.

Reference numeral 6 denotes a piston-shaped second valve body which can slide up and down in the lower valve chamber 1b. Reference numeral 6a denotes a fixed throttle passage connecting the upper back pressure chamber 1g and the lower valve chamber 1b. is there. Also, 7
Is a valve spring provided in the back pressure chamber 1g.
Is biased toward the second valve seat 1c.

Reference numeral 8 denotes a first valve body, which is provided to face the first valve seat 1d so as to be freely movable in the first opening / closing valve body 1e.

FIG. 2 shows an example in which the two-stage expansion valve configured as described above is incorporated in a cooling / heating air conditioning circuit. In the figure, A is an outdoor heat exchanger, B is an indoor heat exchanger, C is a compressor, D is a four-way switching valve, and V is a two-stage expansion valve of the present invention.

The operation of the two-stage expansion valve V of the present invention in the air conditioning circuit of FIG. 2 will be described with reference to FIGS.

FIG. 3 shows a state during the cooling operation. Refrigerant flowing from the outdoor heat exchanger A through the first fluid passage 5 pushes up the first valve body 8 to abut on the first valve seat 1d, and from the first on-off valve chamber 1e to the upper valve via the communication passage 1f. After entering the chamber 2a, the flow is restricted by the needle valve body 3 and flows to the indoor heat exchanger B via the back pressure chamber 1g, the fixed throttle passage 6a, the lower valve chamber 1b, and the second fluid passage 4. At this time, since the first valve body 8 is pressed against the first valve seat 1d, the refrigerant in the first fluid passage 5 does not flow into the lower valve chamber 1b immediately below.

FIG. 4 shows a state during the heating operation. The pressurized refrigerant in the indoor heat exchanger B enters the lower valve chamber 1b from the second fluid passage 4 and reaches the back pressure chamber 1g via the fixed throttle passage 6a. Then, the flow rate is restricted by the needle valve body 3 and flows to the outdoor heat exchanger A via the upper valve chamber 2a, the communication passage 1f, the first opening / closing valve 1e, and the first fluid passage 5. At this time, since the second valve element 6 is pressed against the second valve seat 1c, the refrigerant in the lower valve chamber 1b does not flow directly to the first fluid passage 5.

FIG. 5 shows a state in which the outdoor heat exchanger is defrosted during the heating operation. At this time, when the needle valves are sequentially opened from the state shown in FIG. 4, the flow rate of the refrigerant increases, and the pressure in the back pressure chamber 1g decreases due to the flow resistance of the fixed throttle passage 6a. Moves upward while compressing the valve spring 7 due to the vertical pressure difference, and the second on-off valve is opened. Therefore, most of the incompletely condensed high-temperature refrigerant in the indoor heat exchanger B flows directly from the second fluid passage 4 through the second on-off valve, and flows into the outdoor heat exchanger A from the first fluid passage 5. , Defrosting is performed. During this time, the first on-off valve, which is a check valve, remains open.

The flow characteristics of such a two-stage expansion valve V of the present invention are the sixth.
As shown in the figure.

Embodiment 2 Another example of the two-stage expansion valve of the present invention is shown in FIG. In the present embodiment, the structure of the second valve body 6 in the first embodiment is improved to operate more stably, and the structure of the other parts is the same as that of the first embodiment. It is indicated by.

The back pressure space 1g is provided at the axial center of the second valve body 16 in this example.
A relief passage 16b is provided to connect the relief valve 16 to the relief valve seat 16c formed at the back pressure space 1g side opening of the relief passage 16b. It is provided by being pressed by a spring 7. The relief valve element 10 is provided with an operating rod 10a that penetrates through the relief passage 16b and protrudes toward the first opening / closing valve chamber 1e, and the first valve element 8 contacts the first valve seat 1d. The relief valve element 10 is configured to sometimes push the tip of the operating rod 10a to release the relief valve body 10 from the relief valve seat 16c.

Further, the fixed throttle passage 16a provided in the second valve body 16 is
Control valve seat from near the opening of the second fluid passage 4 on the lower valve chamber 1b side
It is installed diagonally along the line toward 2b, and 1 g of back pressure space
It facilitates the flow of fluid into and out of the device.

The two-stage expansion valve of this embodiment provided with the second valve element 16 having such a structure basically functions in the same manner as the valve of the first embodiment, but for example, as shown in FIG. When incorporated in the circuit, when the first valve body 8 comes into contact with the first valve seat 1d during the cooling / heating operation (the same state as in FIG. 3), the release valve body 10 is opened and the upper surface of the first valve body 8 is opened. The pressure is equalized with the lower valve chamber 1b and becomes low, and the first valve body 8 is securely pressed against the first valve seat 1d by the pressure difference between the first fluid passage 5 and the second fluid passage 4. As a result, it does not occur that the closing force of the valve fluctuates due to fluid leakage from the first on-off valve and the second on-off valve vibrates.

〔The invention's effect〕

The two-stage expansion valve of the present invention can precisely control the flow rate at a low flow rate, so that the capacity of cooling and heating can be increased or decreased according to the load. This makes it possible to constitute a selected heat pump type air conditioner.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an example of a two-stage expansion valve of the present invention, FIG. 2 is an example of a cooling / heating refrigeration circuit using the two-stage expansion valve of the present invention, and FIGS. FIG. 6 is a cross-sectional view illustrating an operation state of the two-stage expansion valve of the present invention. FIG. 6 is a graph showing an example of flow rate characteristics of the two-stage expansion valve of the present invention. It is sectional drawing of an example, FIGS. 8-9 are examples of the conventional refrigeration circuit for cooling and heating. 1 Valve body, 1a Upper lid, 1b Lower valve chamber, 1c Second valve seat, 1d First valve seat, 1e First open / close valve chamber, 1f
Communication passage, 1g ... back pressure chamber, 2 ... partition, 2a ... upper valve chamber, 2b ... control valve seat, 3 ... needle valve body, 4 ... second
Fluid passage, 5 ... first fluid passage, 6,16 ... second valve body, 6a
... fixed throttle channel, 7 ... valve spring, 8 ... first valve body, 9
…… Actuator, 9a …… Male threaded cylinder, 9b …… Rotor,
9e: spring, 10: relief valve, A: outdoor heat exchanger,
B ...... indoor heat exchanger, C ...... compressor, D ...... four-way switching valve, E ...... expansion valve, V ...... two stage expansion valve, S _1, S ₂ ...... solenoid valve.

Claims (5)

(57) [Claims] A first on-off valve capable of blocking only the passage of fluid from a first fluid passage and a second back-pressure operated pilot-type on-off valve capable of blocking only passage of fluid from a second fluid passage are sequentially connected in series. A two-way expansion valve, which is provided between the first fluid passage and the second fluid passage and can continuously control the flow rate, is provided between the first fluid passage and the back pressure space of the second on-off valve; A fixed throttle passage having a flow resistance greater than a flow resistance when the expansion valve is fully opened is provided in the second valve body so as to communicate between the back pressure space and the second fluid passage. Two-stage expansion valve. 2. A control valve seat provided on a partition partitioning an upper valve chamber communicating with a first fluid passage and a lower valve chamber communicating with a second fluid passage, and steplessly advances and retreats from the upper valve chamber side. An expansion valve is formed with a needle valve body, and a piston-like second valve body spring-biased toward a second valve seat communicating with the first fluid passage is slidable up and down in the lower valve chamber. A fixed throttle flow path which is fitted to form a back pressure space between the partition wall and the second valve body and connects the lower valve chamber and the back pressure space, the flow resistance of which is a needle valve; A first valve seat is formed on the side of the first fluid passage of the second valve seat, and the first valve can prevent the inflow of fluid from the first fluid passage. The two-stage expansion valve according to claim 1, further comprising a valve element. 3. The two-stage type according to claim 1, wherein the fixed throttle passage is provided near a line connecting the control valve seat opening of the expansion valve and the second fluid passage opening to the lower valve chamber. Expansion valve. 4. A relief passage connecting the back pressure space and the second valve seat opening to the second valve body, and the relief passage allows only a flow of fluid from the first fluid passage toward the back pressure space. The two-stage expansion valve according to claim 1, further comprising a relief valve body for performing the operation. 5. An operating rod penetrating a relief passage at a tip of a relief valve body, and the operating rod is pushed up by the first valve body when the first valve body closes the first valve seat. The two-stage expansion valve according to claim 4, wherein a tip of the operating rod is formed at a position.