JPH0327263Y2 - - Google Patents

Description

[Detailed description of the invention] This invention is an expansion valve suitable for controlling the flow rate of refrigerant for heat pumps, which can open and close an orifice with a small stroke using a small electromagnet, and has a small and equal amount of leakage from the valve part when heating and cooling is stopped. Regarding.

Conventionally, there was an expansion valve of this type as shown in Utility Model Application No. 196782/1983. (See Figure 4) In this case, an electromagnetic force according to the input current acts on the plunger 1, and as a result, the plunger 1 balances this attraction with the urging force of the spring 3 inserted between the core 2. The opening and closing of the slit 6 is controlled by the spool portion 5 which moves within the sleeve 4 accordingly, and the flow rate of the fluid (refrigerant) is controlled to a desired amount.

However, in such an expansion valve, since magnetic hysteresis occurs in the plunger 1 made of a ferromagnetic material, the displacement position of the plunger differs greatly when the input voltage increases and decreases, and a device to correct this is required. This has the disadvantage that it requires an additional device, making the device expensive.

Furthermore, unless the slit 6 is made elongated in the direction of displacement, the displacement and current will not be proportional. The width of this slit is approximately 1 mm in the case of a household room air conditioner, and in order to perform such machining on the sleeve 4, for example, electric discharge machining, laser machining, etc. must be used, which is expensive.

Next, there is Japanese Patent Application Laid-open No. 137676/1983 (see FIG. 5) which eliminates the drawbacks of the expansion valve shown in FIG. 4. In this case, in order to eliminate the influence of magnetic hysteresis, for example, a pulse signal is sent to the electromagnetic coil for a predetermined period of time with a constant cycle, and by changing this period, the flow rate is changed to perform proportional control.

However, when such a device is used as a flow control valve for a heat pump, the flow direction of the refrigerant from the flow path 10 to the flow path 12 connected to the pipe-shaped valve body 11 is considered as cooling; If heating is performed when the flow is reversed, when the valve body 13 closes the orifice 14, the valve body 13 and the valve body 11
The amount of fluid (refrigerant) leaking from the gap between the air conditioner and the air conditioner differs significantly between cooling and heating, and in one experimental example, the amount leaking during cooling was 5 to 10 times the amount leaking during heating.

That is, during heating, when the operation is stopped, high pressure of refrigerant is applied from the flow path 12 side, so the pressure is uniformly applied to the valve body 13, and the gap between the valve body 11 and the valve body 12 is small, but during cooling, the high pressure of the refrigerant is applied from the flow path 10 side. Because high pressure is applied from
The valve body 13 is pressed against the inner wall of the valve body 11, and the gap becomes large, so that a large amount of high-pressure refrigerant leaks out from the flow path 10 side.

To explain further, in FIG. 6, when the cooling is stopped, high pressure is applied to the flow path 10 side, so the valve body 13 is pressed against the inner wall on the right side in the figure of the valve body 11, and the gap Δl between the valve body 11 and the valve body 13 is is 2Δl, and the amount of leakage increases.

In addition, as mentioned above, in order to reduce leakage during rest, the valve body 12 requires a sealing section _l1 as shown in Fig. 5. This is usually 1 to 3 mm, and the longer side of this sealing section is The amount of leakage will be reduced.

Next, considering the orifice 14, its diameter is 0.5 to 5 mm in a room air conditioner, a car air conditioner, or a 10 package air conditioner. Therefore, in this case, in order to control the flow rate of the refrigerant, the valve body 12 needs to oscillate by the length of the seal length _l1 plus the orifice diameter.For example, if the seal length is 1.5 mm and the orifice diameter is 3 mm, the valve body 12 must be moved up and down by 4.5 mm by ON/OFF pulses, and as this stroke increases, the electromagnetic force increases, which requires a large volume electromagnet and has the disadvantage of increasing power consumption. was.

This proposal was devised in view of the above problems.
According to the present proposal, there is provided a cylindrical valve body having a first passage, a second passage communicating with the first passage via an orifice, an electromagnetic coil provided in the valve body, and a cylindrical valve body having a second passage communicating with the first passage through an orifice. An electromagnetic control section consisting of an attractor provided in a frame, a plunger that moves by the operation of the electromagnetic coil, a first spring inserted between the attractor and the plunger, and a slider that slides inside the valve body. a piston-shaped valve body that moves and has one end fixed to the plunger to open and close the orifice; a second spring that presses the valve body together with the plunger toward the suction element; and a second spring that is common to the plunger and the valve body. The problem described above can be solved by providing an annular groove in the inner periphery of the valve body that is connected to the orifice, has a width larger than the diameter of the orifice, and is larger than the diameter of the piston in a valve with an opening pressure equalizing hole. This solves the problem.

In such an expansion valve, the valve body moves up and down due to the balance between the electromagnetic force generated by the input pulse signal applied to the electromagnetic coil and the two springs, thereby opening and closing the groove. Since this groove is annularly provided in the valve body with a width larger than the diameter of the orifice and communicates with the orifice, a slight stroke of the valve body can open the groove.
In other words, even if the orifice is opened and closed, and high-pressure refrigerant acts on the side surface of the valve body through the orifice when cooling operation is stopped, the gap between the valve body and the valve body remains unchanged, and refrigerant leakage is uniform and minimal. However, as mentioned above, since the stroke of the valve body may be small, the flow rate of the refrigerant can be controlled using a small electromagnet.

In addition, the pulse signal described above can be obtained by, for example, changing the opening and closing times of the groove provided in the valve body, that is, by keeping the cycle constant and changing the ratio of opening and closing times. By changing the opening degree of the groove, the flow rate of the refrigerant can be controlled without any influence of hysteresis.

Next, an embodiment of the present invention will be described with reference to the drawings.
The cylindrical valve body 20 is provided with a first passage 21 and a second passage 23 that is orthogonal to the first passage and communicates with the orifice 22 and the center hole 20a of the valve body. .

A pipe 24 is provided in the upper electromagnetic control section A of the valve body 20 in the figure, and an electromagnetic coil 25 is provided around the outer periphery of this pipe 24. 26 is a frame for the electromagnetic coil, and 27 is a housing surrounding the electromagnetic coil.
Reference numeral 28 denotes an attractor made of a magnetic material, and is fixed to the top back surface of the housing 27 with a machine screw 29. A plunger 30 is provided within the pipe 24 facing the suction element 28. A first spring 31 is interposed between the suction element 28 and the plunger 30.

In the diagram of the plunger 30 of the electromagnetic control unit A, the upper end of a piston-shaped valve body 32 is connected to the lower part by appropriate means, and this valve body moves into the center hole 20 of the valve body 20 in response to the operation of the plunger 30.
Slide inside a. The lower end of this valve body 32 and the second
A second spring 33 is inserted between the flow path 23 and the flow path 23 .

However, this second spring 33 presses the valve body 32 toward the plunger 30 to operate, and its urging force may be sufficiently weaker than that of the first spring 31. The plunger 30 and the valve body 32 are provided with pressure equalizing holes 34, one of which opens on the suction element 28 side, and the other opens on the second flow path 23 side.

An annular groove 35 communicating with the orifice 22 is provided in the center hole 20a of the valve body 20. This groove 35 has a width L ₂ larger than the diameter d ₁ of the orifice 22.
and has a diameter d ₃ larger than the diameter d ₂ of the central hole of the valve body 20.

Now, let L ₁ be the distance between the lower surface of the groove 35 and the lower end of the valve body 32, and L ₃ be the distance between the upper surface of the groove 35 and the point where the valve body 20 and the pipe 24 abut,
These L ₁ and L ₃ are heating (or cooling) of the expansion valve of this invention
This serves as a seal that prevents high-pressure refrigerant from leaking to the low-pressure side when the product is not in use.

Then, a current is applied to the electromagnetic coil 25 of this expansion valve in a manner as shown in FIG. 2, for example. That is, the ON time t ₁ or OFF time t ₂ is changed while keeping the period T constant, and the valve body 3 is activated by such a pulse signal.
The refrigerant flow rate can be controlled by moving the groove 2 up and down as described later to change the opening degree of the groove 35 on a time average basis. In other words, as shown in the upper part of Figure 2, if the ON time t ₁ is shortened, the flow rate becomes small, and as shown in the middle part, if the ON time t ₁ is set to a medium value, the flow rate becomes medium, and further as shown in the lower part. ON time like
The longer t ₁ , the higher the flow rate.

Therefore, since the valve body 32 moves up and down by completely opening or closing the groove 35, it is necessary to control the spool portion 5 so that the slit 6 opens halfway, as in the conventional control valve shown in FIG. Therefore, there is no effect of hysteresis, which has been a problem with such control valves.

In such an expansion valve, the present invention operates and produces effects as follows.

That is, due to the balance between the electromagnetic force generated by the input pulse signal applied to the electromagnetic coil 25 and the springs 31 and 33, the plunger 30 and the valve body 32 move up and down to open and close the groove 35 provided in the valve body 20. do.

However, as mentioned above, the diameter of the orifice 22 is
If d ₁ is the inner diameter of the center hole of the valve body 20, d ₂ is the distance from which the lower end of the valve body 32 passes the lower edge of the groove 35 to open the groove, then π/4d ² ₁ = πd ₂ ΔL. The formula holds true, and the valve body 32 only needs to move up and down by ΔL and the seal portion L ₁ that satisfy this formula, so that a predetermined amount of refrigerant is transferred, for example, from the first flow path 21 to the second flow path 21.
It flows to the flow path 23 side.

The above formula becomes ΔL=d〓/4d ₂ , and now if d ₂ = 7mm and d ₁ = 3mm, ΔL=3 ² /4×7=0.3mm, and the length of the seal part is set to 1.5mm as above. It can be seen that the stroke of the vertical movement of the valve body 32 is only 1.8 mm, which is less than half that of the conventional one.

Therefore, according to the present invention, the same purpose can be achieved with small electromagnetic force and small electric power.

Next, considering the case where the operation is stopped, if the refrigerant flow direction is for cooling in the direction of the dotted line arrow and for heating in the direction of the solid line arrow, during heating, high pressure is applied from the second flow path 23 side, so the valve body 32, pressure is applied uniformly, and the gap between the valve body 20 and the valve body 32 is uniform and small. That is, there is little refrigerant leakage. Also, when cooling, the first
High pressure is applied from the flow path 21 side, but this pressure is applied from the orifice 22 to the area around the valve body 32 through the groove 35, so the valve body 32 is not connected to the valve body as in the conventional case, as shown in FIG. A gap G that is located at the center of the valve body 20 without deviation and is formed between the two.
is uniform, so the refrigerant leakage is also uniform,
This is far less than the conventional one and is the same as the leakage during heating.

As described above, according to the present invention, it is possible to provide an expansion valve with good controllability because it operates with a small electromagnet (low electric power) and the amount of refrigerant leaking from the valve part is small and equal when heating and cooling is stopped. be.

[Brief explanation of the drawing]

FIG. 1 is a schematic longitudinal sectional view of the expansion valve of the present invention, FIG. 2 is an example of the waveform of an input pulse applied to the electromagnetic coil of the expansion valve of the present invention, and FIG. 3 is a sectional view taken along the - line in FIG. 1. FIG. 4 is a schematic vertical sectional view of an example of a conventional expansion valve, FIG. 5 is a schematic vertical sectional view of another example of the conventional expansion valve, and FIG. 6 is a schematic vertical sectional view of an example of a conventional expansion valve. FIG. 3 is an enlarged cross-sectional view showing a state in which the valve body is pressed against the valve body side. 20... Valve body, 21... First flow path, 22...
... Orifice, 23 ... Second flow path, 25 ... Electromagnetic coil, 28 ... Attractor, 30 ... Plunger, 31 ... First spring, 32 ... Valve body, 33 ...
...Second spring, 34...Pressure equalization hole, 35...Annular groove.

Claims (1)

[Scope of utility model registration request] A cylindrical valve body having a first flow path and a second flow path communicating with the first flow path via an orifice, an electromagnetic coil provided in the valve body, and an electromagnetic coil provided within the frame of the electromagnetic coil. an electromagnetic control section consisting of a plunger which is moved by the operation of the electromagnetic coil; a first spring inserted between the attractor and the plunger; A piston-shaped valve body fixed to the plunger to open and close the orifice, a second spring that presses the valve body together with the plunger toward the suction element, and a pressure equalization hole that is commonly opened to the plunger and the valve body. communicating with the orifice and having a width larger than the diameter of the orifice,
An expansion valve in which an annular groove larger than the diameter of the piston is provided on the inner periphery of the valve body.