JPH0118864Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a screw compressor with a capacity control slide valve that compresses gas by rotating a pair of screw rotors that mesh with each other in a rotor chamber.

For example, a screw compressor used in a refrigerator stops with the slide valve located at the load position due to the state of the refrigerant in the refrigeration system. On the other hand, at startup, the slide valve is moved to the unload position to prevent liquid compression and reduce the load, but this occurs rapidly. If the slide valve is moved rapidly during operation, hunting will occur, so it is necessary to move the slide valve slowly. Since the difference in these speeds is large, conventionally a hydraulic piston that operates the slide valve is operated by a hydraulic circuit as shown in FIG.

In Fig. 4, 15 is a slide valve, 13 is a piston, 14 is a piston rod connected to the slide valve 15, 16 is a pressure cylinder chamber, and 17 is a low-pressure cylinder chamber communicating with the compressor suction side, which is rapidly unloaded at startup. In this case, the pressure oil sent from the piping 21 from the hydraulic source branches to open the parallel solenoid valves 22 and close the solenoid valves 24 in the piping connecting the pressure cylinder chamber 16 and the low pressure cylinder chamber 17.
Pressure oil enters the pressure cylinder chamber 16 and piston 1
3 moves to the right and rapidly moves the slide valve 15 to the unload position.

To increase the load during operation, close the solenoid valves 22 and 23 and open the solenoid valve 24 to counter the pressure applied to the discharge side of the slide valve 15.
The flow rate is adjusted at 6 and flows into the low pressure cylinder chamber 17 side through the solenoid valve 24 and further through the throttle valve 26, and the back pressure is added to the pressure cylinder chamber 16, and the thrust of the piston 13 and the sliding valve 15
The slide valve 15 is operated slowly by reducing the thrust difference based on the discharge pressure applied to the slide valve 15. To unload, the solenoid valve 24 is closed, and when the solenoid valve 23 is opened, the pressure oil throttled by the throttle valve 25 is transferred to the pressure cylinder chamber 16.
and move the slide valve 15 to the right at a slow speed. When all the solenoid valves are closed, the slide valve 15 is held at a fixed position. In the conventional example, the circuits for rapid operation and normal operation were separated and the pressure oil supply circuits for rapid operation and normal operation were switched, making the piping system complicated.

The purpose of this invention is to simplify the pressure oil supply circuit that supplies pressure oil to the hydraulic cylinder for controlling the slide valve of the screw compressor.

In this device, male and female rotors, each having a screw thread and a thread groove on the outer periphery with mutually interlocking leads, are rotatably supported in a casing equipped with a suction port and a discharge port, with their outer peripheries in close contact with each other. A slide valve is provided in close proximity to the outer periphery of the male and female rotors so as to be able to slide on each other, a piston rod of a hydraulic cylinder that moves the slide valve is connected to the slide valve, and one cylinder chamber of the hydraulic cylinder opposes the thrust of the slide valve. Forming a pressure cylinder chamber,
The other cylinder chamber constitutes a low-pressure cylinder chamber that communicates with the compressor intake side, and is provided with a pressure oil supply circuit that communicates with the pressure cylinder chamber from a hydraulic source, and communicates between the pressure cylinder chamber and the low-pressure cylinder chamber via an on-off valve and a throttle valve. In this system, pressure oil is supplied from the hydraulic source to the pressure cylinder chamber through an on-off valve whose flow path is completely cut off when fully closed, and an on-off valve whose flow path is narrowed and communicated even when fully closed. It is a screw compressor equipped with a circuit.

Embodiments of this invention will be described below with reference to the drawings. Figure 1 is a vertical sectional view of the screw compressor, Figure 2
The figure is a sectional view taken along the line AA in FIG. 1.

Both sides of the rotor casing 1 form a suction side end wall and a discharge side end wall, which are sealed by a suction casing 2 and a discharge casing 3, and a male rotor 4 and a female rotor 5 having shapes as shown in FIG. 2 are engaged with each other. Both rotors are in contact with the bicircular arc-shaped outer periphery of the casing 1 on the discharge side. When both rotors rotate in the direction of the arrow shown in the figure, the positions where they engage each other gradually move even though they have the same lead.The male rotor 4 and female rotor 5, which engage with each other by providing thread grooves and threads with large leads on their outer peripheries, The integrated shaft part supports a radial load by a journal bearing fitted into the suction casing 2 and a journal bearing fitted into the discharge casing 3, respectively, and its axial movement is restrained by a thrust ball bearing fitted into the discharge casing 3. ing.

The suction casing 2 is provided with a suction passage 6 in the upper part, and a suction port 7 is opened at a position on the upper end surface between the male rotor 4 and the female rotor 5. A discharge port 8 is provided on the end face of the discharge casing 3 opposite to the position below the suction port 7 where the male rotor 4 and female rotor 5 meet, and a discharge passage 9 in the discharge casing 3 communicates with the outside of the machine. ing.

A cylinder 11 is fitted into the suction casing 2 and is hermetically pressed by a cover 12 fixed to the suction casing 2.

A piston 13 sealed by a sealing ring is fitted into the cylinder 11, and the piston rod 1
4 extends into the rotor casing 1 and is fixed to a slide valve 15 that changes the suction side volume to adjust the suction amount.

A pressure cylinder chamber 16 is formed between the piston 13 and the cover 12, and a low pressure cylinder chamber 17 with the piston 13 in between has the same pressure as the chamber on the low pressure control edge side of the slide valve 15 through a communication hole 18.
This chamber is also connected to the suction port 7 side. An oil supply port 19 opens into the pressure cylinder chamber 16 .

FIG. 1 also shows a hydraulic circuit diagram for supplying pressure oil to the slide valve control cylinder. A solenoid valve 31 which assumes a fully closed and fully open position and a solenoid valve 32 whose valve port is slightly open even when fully closed are arranged in series in a pipe 21 to which pressure oil is supplied from a hydraulic source (not shown), and an oil supply port. Connects to 19. The pressure cylinder chamber 16 and the low pressure cylinder chamber 17 are connected by a pipe 35 via a solenoid valve 33 and a throttle valve 34.

The solenoid valve 32 is connected to the valve body 3 as shown in FIG.
Adjustment rod 3 screwed into and out of 6 in a sealed manner
7 serves as a stopper for the valve body 38, which is energized downward by the spring 40, and when the solenoid 39 is deenergized, the valve body 38 hits the end of the adjustment rod 37, creating a gap between the valve seat 41 and the valve body 38. or the valve body 38 has a small hole 4 in the partition wall between the inlet side and the outlet side of the valve body 36 that is in close contact with the valve seat 41.
2 may be provided. The solenoid valve 31 is a normal solenoid valve that completely blocks the flow path when closed.

When starting the screw compressor, the solenoid valves 31 and 32
is open, and the solenoid valve 33 is closed. Therefore, a large amount of pressure oil is sent to the pressure cylinder chamber 16, causing the piston 13 to rapidly move to the right, and the slide valve 15 to be entangled, rapidly move to the right and assume a fully open position.

To apply a load during operation, the solenoid valve 31 is closed, and when the solenoid valve 33 is opened, the thrust of the slide valve 15 due to the discharge pressure causes the piston 13 to move to the left, and the oil in the pressure cylinder chamber 16 is discharged from the pressure oil supply port 19. Then, it passes through the solenoid valve 33 and flows into the low-pressure cylinder chamber 17 side while being throttled by the throttle valve 34, so back pressure is generated in the pressure cylinder chamber 16 by the throttle valve 34, giving an appropriate resistance to the slide valve 15. No sudden load is applied to the screw compressor.

When the electromagnetic valve 33 is closed in this state, even though the thrust of the slide valve 15 is applied to the piston 13, the oil in the pressure cylinder chamber 16 cannot flow out, so the slide valve 15 is held at a fixed position.

To unload from the operating state, as in the case of increasing the load, it is necessary to move the slide valve 15 at an appropriate speed to avoid hunting due to rapid movement of the slide valve 15. In this case, the solenoid valve 31 is opened and the solenoid valves 32 and 33 are closed. The pressure oil passes through the solenoid valve 31 from the piping 21, is throttled by the solenoid valve 32, and enters the pressure cylinder chamber 16 through the oil supply port 19. Since the flow rate of pressure oil is small, the piston 13 moves slowly to the right and closes the slide valve 15.
Move to the right to reduce the load. When the solenoid valve 31 is closed at a required position, the slide valve 15 stops.

Although the embodiment is a solenoid valve, other types of on-off valves may be used.

As described above, in the pressure cylinder chamber of the hydraulic cylinder for controlling the slide valve, an on-off valve that opens and closes fully, and an on-off valve that has a fully open position and a fully closed position, and that allows a small amount of oil to flow in the fully closed position, are arranged in series. Because pressure oil is supplied, the functionality remains unchanged and piping is simplified.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional view of the screw compressor, Fig. 2 is a sectional view taken along line A-A in Fig. 1, Fig. 3 is a longitudinal sectional view of some of the valves in Fig. 1, and Fig. 4 is a longitudinal sectional view of a conventional example. It is an oil piping diagram. 1... Rotor casing, 2... Suction casing, 3... Discharge casing, 4... Male rotor, 5
...Female rotor, 6...Suction passage, 7...Suction port,
8...Discharge port, 9...Discharge passage, 11...Cylinder, 12...Cover, 13...Piston, 14...
...Piston rod, 15...Slide valve, 1
6...Pressure cylinder chamber, 17...Low pressure cylinder chamber, 18...Communication hole, 19...Oil supply port, 21...
...Piping, 31, 32, 33...Solenoid valve, 34...
Throttle valve, 35...piping.

Claims (1)

[Scope of utility model registration request] A male and female rotor, which has screw threads and thread grooves on the outer periphery with mutually engaging leads, is rotatably supported in a casing equipped with a suction port and a discharge port, with the outer periphery in close contact with each other, and the rotor slides on a part of the casing wall. A slide valve is provided as close as possible to the outer periphery of the male and female rotors, a piston rod of a hydraulic cylinder that moves the slide valve is connected to the slide valve, and one cylinder chamber of the hydraulic cylinder is a pressure cylinder chamber that opposes the thrust of the slide valve. The other cylinder chamber constitutes a low-pressure cylinder chamber that communicates with the compressor intake side, and is provided with a pressure oil supply circuit that connects to the pressure cylinder chamber from a hydraulic power source, as well as an on-off valve and a throttle valve in the pressure cylinder chamber and the low-pressure cylinder chamber. In the case where the hydraulic pressure source is connected to the pressure cylinder chamber through an on-off valve whose flow path is completely cut off when fully closed, and an on-off valve whose flow path is narrowed and communicated even when fully closed. A screw compressor equipped with a pressure oil supply circuit.