JPS6030432B2 - evaporation pressure control valve - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in an evaporation pressure control valve used to always maintain a constant evaporation pressure in an evaporator.

As shown in Fig. 1, the pilot type evaporation pressure control valve is arranged inside a case, and inside a cylinder 2 that partitions an upstream side (primary pressure side) A and a downstream side (tertiary pressure side) B is a main valve. A valve 3 is slidably fitted with iron, and the amount of refrigerant passing through is controlled by the closed area (in the fluid passage) of the main passage formed by the hole 4 formed in the cylinder 2 and the hole 5 of the main valve 3. .

The secondary pressure chamber 7 consisting of the main valve 3 and the cylinder 2 is
The air is passed to the downstream side B through a relief hole 8 formed at The pilot valve 10 is fixed to a diaphragm 11 which is a pressure detection part, and the pressure on the upstream side A (evaporation pressure) passes through the hole 13 of the case and compresses the inert gas in the reference pressure chamber 12 via the diaphragm 11. Displaced by
The pilot hole 9a provided in the pilot passage 9 is opened and closed to supply the commanded pressure from the pilot valve 10 to the secondary pressure chamber 7.

Therefore, the position is determined by the balance between the force in the downstream direction caused by the difference between the pressure in the secondary pressure chamber 7 and the pressure on the downstream (tertiary pressure) side B and the force with the spring 6, and the main path is closed. The area (in the fluid path) is determined. In such an evaporation pressure control section, when the heat load is small and the main valve moves to the left to close the main passage, the oil bleed hole 14 formed in the main valve 3 will open in the cylinder 5 as shown in FIG. A small amount of the refrigerant on the primary pressure side A passes through the hole 4 to the tertiary pressure side (the suction side of the compressor).
B so as not to interfere with the drive of the compressor.

However, since this oil bleed hole 14 is a fixed hole, its diameter is a problem. For example, if the amount of oil bleed is determined according to the low speed rotation of the compressor, the characteristics shown in Fig. 3 can be obtained at low speed. Even when the main valve 3 is fully closed (the main passage is fully closed), the tertiary pressure is higher than the preferable lower limit P of the tertiary pressure, which is a satisfactory state.

However, at high speed rotation, even if the main valve 3 moves, the main passage is closed, the oil bleed hole 14 is opened, and cold soot flows from the primary pressure side A to the tertiary pressure side B, the combustor does not rotate at high speed. The tertiary pressure on the tertiary pressure side B falls below the preferable lower limit P of the tertiary pressure shown in Fig. 4, making it impossible to obtain the minimum necessary flow of cold soot to the compressor, resulting in poor lubrication of the compressor, and the drive of the compressor. This will cause problems.

Therefore, it is preferable for the diameter of the oil bleed hole 14 to be large when the compressor rotates at high speed and small when the compressor rotates at low speed. However, if it is set to a large diameter, the amount that flows out from the oil bleed hole 14 during low speed rotation will increase the evaporation pressure (pressure). This may cause the evaporator to freeze and the effectiveness of the evaporation pressure control valve to be lost.

For this reason, the present invention sets the diameter of the oil bleed hole 14 according to the low-speed rotation of the compressor, and opens the main passage during high-speed rotation from the primary pressure side A to the tertiary pressure side B.
The structure is such that the cylinder 2 is provided with a passage 15 that connects the primary pressure side A and the secondary pressure chamber 7, and the passage 15 is configured to respond to a predetermined pressure difference. A valve 16 that is opened and closed is provided, and when the secondary pressure chamber 7 approaches the preferable lower limit P of the tertiary pressure, the valve 16 opens to allow the primary pressure to flow from the primary pressure side A to the secondary pressure chamber 7. The pressure in the secondary pressure chamber 7 is increased, the main valve 3 is shifted to the left, and the cold soot on the primary pressure side A flows from the main passage to the tertiary pressure side B, eliminating the shortage of refrigerant during high-speed rotation, and reducing the tertiary pressure. This prevents the compressor from decreasing and causing problems with the compressor.

Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 5, an embodiment of the present invention is shown, which has the same structure as a conventional pilot-type evaporation pressure control valve, and which has the same structure as the conventional pilot-type evaporation pressure control valve, and which is adapted to be connected between the primary pressure (evaporation pressure) side A of the cylinder 2 and the secondary pressure chamber 7. A hole 15 is opened, and a valve 16 that opens and closes in response to the pressure difference between the two chambers is provided in the hole 15.

This valve 16 has a structure that allows the flow to flow from the primary pressure side A to the secondary pressure chamber 7.
A rod 16a is seated at the closed end of the side and inserted into the hole 15.
The valve 16 protrudes toward the next pressure side A, and a spring 16b interposed between the protruding end and the cylinder 2 biases the valve 16.
This opening/closing operation of the valve 16 is performed by the compressor rotating at high speed.
Moreover, when the heat load is low, the main valve 3 moves to the left and closes the main passage, and the oil bleed hole 14 closes, but the amount of cold soot that will flow out tends to be insufficient.
The tertiary pressure on the tertiary pressure side decreases, and along with this decrease in tertiary pressure, the pressure in the secondary pressure chamber 7 also decreases through the relief hole 8, and the secondary pressure is near the preferable lower limit P on the tertiary pressure side. When it approaches <, the pressure difference △P between the primary pressure and the secondary pressure becomes a predetermined pressure, the valve 16 moves against the spring 16b and opens, and the primary pressure is released from the primary pressure side A through the hole 15. It begins to flow into the secondary pressure chamber 7.

Therefore, the pressure within the secondary pressure chamber 7 increases, pushing the main valve 3 to the left and moving it. This allows the main passage (cylinder 2
(consisting of the hole 4 of the main valve 3 and the hole 5 of the main valve 3) are slightly opened as shown in the figure so that the primary pressure can flow through the main passage to the tertiary pressure side B, and this main passage It becomes possible to secure the minimum required amount with the flow rate from . Therefore, the tertiary pressure also maintains the preferable lower limit P of the tertiary pressure, and the increase in the tertiary pressure prevents the occurrence of malfunctions in the drive of the compressor. Such characteristics are shown in Fig. 6, where the main passage is slightly opened at low load, and the secondary and tertiary pressures are at the preferable lower limit P of the tertiary pressure.
It is near.

The above explanation explains the opening and closing of the valve 16 when the compressor is rotating at high speed and the heat load is low. However, when the compressor is rotating at low speed, the pressure on the tertiary pressure side B is also higher than the lower limit P of the tertiary pressure side. The pressure is maintained, so the pressure difference between the primary pressure and the secondary pressure is smaller than the valve opening predetermined pressure.
The valve 16 is closed, there is no inflow through the hole 15, and control is performed with the same characteristics as shown in FIG. 3 as for the slave. The pressure difference that determines the opening and closing of the valve 16 is determined by the force of the spring 16b, and by appropriately selecting the force of this spring 16b, it is possible to adjust the opening of the main passage for oil bleed during high speed rotation and low load. It is possible.

The embodiment of the present invention has been described above, but in order to avoid repeating the explanation, the same parts as in the conventional example (FIG. 1) have been given the same numbers and the explanation has been omitted.

As described above, the present invention provides a pilot-type evaporation pressure control valve in which a cylinder is provided with a passage connecting a primary pressure side and a secondary pressure chamber, and the passage is opened and closed in response to a pressure difference. The valve opens when a predetermined pressure difference is reached.
The next side causes pressure to flow into the secondary pressure chamber, increasing the pressure in the secondary pressure chamber, and then moving the main valve to slightly open the main passage, and from this main passage, cold soot is transferred from the primary pressure side to the tertiary pressure chamber. The oil flows to the pressure side, thereby increasing the outflow amount and ensuring the amount of oil bleed during high-speed rotation and low heat load.

[Brief explanation of the drawing]

Figure 1 is a sectional view of a conventional pilot-type evaporation pressure control valve, Figure 2 is an enlarged sectional view of the main parts of the same, Figure 3 is a characteristic diagram of the same compressor at low speed rotation, and Figure 4 is the same as the same. FIG. 5 is an enlarged sectional view of the main part of the present invention, and FIG. 6 is a characteristic diagram of the present invention when the compressor rotates at high speed. 2...Cylinder, 3...Main valve, 7...
...Secondary pressure chamber, 15...hole, 16...
·valve. Figure 2 Figure 3 Figure 5 Figure 4 Figure 6

Claims (1)

[Claims] 1 The pilot valve is moved by the pressure inside the evaporator, and the commanded pressure from the pilot valve moves the main valve in the cylinder that separates the primary pressure side and the tertiary pressure side to adjust the opening degree of the main passage and reduce the evaporation pressure. In the evaporation pressure control valve, the cylinder is provided with a passage communicating between the primary pressure side and the secondary pressure chamber, and the passage is provided with a valve that opens and closes in response to a pressure difference. An evaporation pressure control valve that opens when a difference occurs, allowing pressure to flow from the primary side to the secondary pressure chamber.