A screw compressor with a four-solenoid valve for automatically and steplessly and efficiently adjusting the content volume ratio and a control method thereof

Abstract

The present invention belongs to a screw compressor with an automatic stepless and efficient adjustment of internal volume ratio and a control method. The problems to be solved are those existing in the background technology: when adjusting the internal volume ratio, the compressor cannot maintain a full-load state, which affects the COP of the compressor; two slide valves need to continuously correct their positions, and the accuracy of the internal volume ratio adjustment of the compressor is poor. The key points of the technical solution adopted to solve this technical problem are: the two ends of the A solenoid valve are connected to the a chamber and the b chamber through an external oil pipeline, and the two ends of the B solenoid valve are connected to the c chamber and the d chamber through an external oil pipeline. When the internal volume ratio increases, the C solenoid head and the A solenoid valve are opened; when the internal volume ratio decreases, the B solenoid head and the B solenoid valve are opened; when the internal volume ratio reaches the specified position, all solenoid valves and solenoid heads are closed. It is applied to a screw compressor with an automatic stepless and efficient adjustment of internal volume ratio.

Description

Technical Field

[0001] The present invention belongs to the field of refrigeration equipment and technologies, and more specifically, relates to a screw compressor with an automatic stepless and efficient regulation of internal volume ratio by four solenoid valves and a control method therefor. Background Art

[0002] Energy conservation is the top priority in the energy field. To address the issue of energy inefficiency caused by over-compression and under-compression in screw compressors, screw compressors capable of adjusting the internal volume ratio have been invented. There are two types of adjustment methods: one is manual stepwise adjustment, and the other is automatic adjustment. Manual stepwise adjustment of the internal volume ratio is applicable to stable operating conditions with large seasonal variations between winter and summer, or when there are significant changes in operating conditions, such as converting a low-temperature storage to a high-temperature storage. Automatic adjustment of the internal volume ratio can adjust the internal volume ratio in real time according to the changes in the suction and discharge pressures of the screw compressor, that is, it can truly achieve equal internal and external pressure ratios, eliminate over-compression and under-compression, and greatly improve the COP of the compressor. Currently, the common problems in the industry for automatic adjustment of the internal volume ratio are as follows: the adjustment of the internal volume ratio and the energy adjustment are controlled by two independent solenoid valve groups. Moreover, due to the incompressible nature of lubricating oil, when the internal volume ratio needs to be adjusted, the internal volume ratio adjustment slide valve and the energy adjustment slide valve separate from the mutually attached state, and the compressor cannot maintain a full-load state, which affects the COP of the compressor; during the process of adjusting the internal volume ratio, the position when the internal volume ratio adjustment slide valve and the energy adjustment slide valve reattach to each other often deviates. It is difficult for the internal volume ratio slide valve to accurately stop at the required position in one go, and the two slide valves need to continuously correct their positions, or a large deviation amount is set, resulting in poor accuracy of the internal volume ratio adjustment of the compressor. Summary of the Invention

[0003] The object of the present invention is to provide a screw compressor and a method for automatically and steplessly and efficiently adjusting the internal volume ratio, so as to solve the problems existing in the background technology: when the internal volume ratio is adjusted, the compressor cannot maintain a full-load state, which affects the COP of the compressor; the two slide valves need to continuously correct their positions, and the accuracy of the internal volume ratio adjustment of the compressor is poor. The technical solution adopted to solve this technical problem is: a screw compressor for automatically and steplessly and efficiently adjusting the internal volume ratio with four solenoid valves. The inner cavity of the oil cylinder body is separated into an energy adjustment piston cavity and an internal volume ratio adjustment piston cavity by an intermediate partition. The energy adjustment piston cavity is separated into cavity a and cavity b by an energy adjustment piston. The internal volume ratio adjustment piston cavity is separated into cavity c and cavity d by an internal volume ratio piston. The energy adjustment piston is connected to an energy adjustment slide valve through an energy adjustment guide rod. The internal volume ratio piston is connected to an internal volume ratio slide valve through an internal volume ratio guide rod. An energy adjustment electromagnetic reversing valve and an internal volume ratio adjustment electromagnetic reversing valve are connected to the oil cylinder body. The A solenoid head controls the communication between cavity a and the oil supply channel, and the communication between cavity b and the oil return channel. The B solenoid head controls the communication between cavity a and the oil return channel, and the communication between cavity b and the oil supply channel. The C solenoid head controls the communication between cavity c and the oil supply channel, and the communication between cavity d and the oil return channel. The D solenoid head controls the communication between cavity c and the oil return channel, and the communication between cavity d and the oil supply channel. It is characterized in that: the two ends of the A solenoid valve are connected to cavity a and cavity b through an external oil pipeline. The two ends of the B solenoid valve are connected to cavity c and cavity d through an external oil pipeline. A control method for a screw compressor for automatically and steplessly and efficiently adjusting the internal volume ratio with four solenoid valves as described above is characterized in that: when the internal volume ratio increases, the C solenoid head and the A solenoid valve are opened; when the internal volume ratio decreases, the B solenoid head and the B solenoid valve are opened; when the internal volume ratio reaches the specified position, the four solenoid valves of the energy adjustment electromagnetic reversing valve, the internal volume ratio adjustment electromagnetic reversing valve, the A solenoid valve, and the B solenoid valve are closed, and the A solenoid head, the B solenoid head, the C solenoid head, and the D solenoid head are closed. Among them, the energy adjustment electromagnetic reversing valve and the internal volume ratio adjustment electromagnetic reversing valve are selected to be connected to the oil cylinder body through an external oil pipeline. The A solenoid valve and the B solenoid valve are selected to be directly connected to the oil cylinder body.

[0004] The beneficial effects of the present invention compared with the prior art are as follows: By adopting the above technical solution, on the one hand, when the internal volume ratio increases, open the C solenoid valve, the c chamber is filled with oil and the d chamber returns oil, open the A solenoid valve, the a chamber and the b chamber are connected. Under the combined action of the oil inlet pressure, the oil return pressure, the exhaust pressure and the suction pressure, the internal volume ratio slide valve pushes the energy regulating slide valve to move to the right. When the internal volume ratio decreases, open the B solenoid valve, the b chamber is filled with oil and the a chamber returns oil, open the B solenoid valve, the c chamber and the d chamber are connected. Under the combined action of the oil inlet pressure, the oil return pressure, the exhaust pressure and the suction pressure, the energy regulating slide valve pushes the internal volume ratio slide valve to move to the left. During the process of the change of the internal volume, the two slide valves always remain in contact with each other, that is, when adjusting the internal volume ratio under the full load state, the compressor always maintains high efficiency. On the other hand, when the internal volume ratio reaches the specified position, close all solenoid valves, and the energy regulating slide valve and the internal volume ratio slide valve stop moving while being in contact with each other, which greatly reduces the difficulty of program control and enables the screw compressor to obtain the required internal volume ratio more quickly and accurately, with high efficiency and energy saving. BRIEF DESCRIPTION OF THE DRAWINGS

[0005] Figure 1 is a schematic structural diagram of the present invention. Figure 2 is a schematic diagram of the internal oil circuit connection in the electromagnetic reversing valve. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0006] Example 1: Refer to Figure 1 、 Figure 2, a screw compressor with a four-solenoid valve for automatically and steplessly adjusting the internal volume ratio efficiently. The inner cavity of the oil cylinder body 1 is separated into an energy regulation piston cavity and an internal volume ratio regulation piston cavity by an intermediate partition 7. The energy regulation piston cavity is separated into cavity a and cavity b by an energy regulation piston 6. The internal volume ratio regulation piston cavity is separated into cavity c and cavity d by an internal volume ratio piston 8. The energy regulation piston 6 is connected to an energy regulation slide valve 12 through an energy regulation guide rod 9. The internal volume ratio piston 8 is connected to an internal volume ratio slide valve 11 through an internal volume ratio guide rod 10. An energy regulation electromagnetic reversing valve 2 and an internal volume ratio regulation electromagnetic reversing valve 3 are connected to the oil cylinder body 1. An A electromagnetic head 21 controls the communication between cavity a and the oil supply passage, and the communication between cavity b and the oil return passage. A B electromagnetic head 22 controls the communication between cavity a and the oil return passage, and the communication between cavity b and the oil supply passage. A C electromagnetic head 31 controls the communication between cavity c and the oil supply passage, and the communication between cavity d and the oil return passage. A D electromagnetic head 32 controls the communication between cavity c and the oil return passage, and the communication between cavity d and the oil supply passage. It is characterized in that: the two ends of an A solenoid valve 4 are connected to cavity a and cavity b through an external oil pipeline. The two ends of a B solenoid valve 5 are connected to cavity c and cavity d through an external oil pipeline. A control method for a screw compressor with a four-solenoid valve for automatically and steplessly adjusting the internal volume ratio as described above, is characterized in that: when the internal volume ratio increases, the C electromagnetic head 31 and the A solenoid valve 4 are opened; when the internal volume ratio decreases, the B electromagnetic head 22 and the B solenoid valve 5 are opened; when the internal volume ratio reaches a specified position, the four solenoid valves, namely the energy regulation electromagnetic reversing valve 2, the internal volume ratio regulation electromagnetic reversing valve 3, the A solenoid valve 4, and the B solenoid valve 5, are closed, and the A electromagnetic head 21, the B electromagnetic head 22, the C electromagnetic head 31, and the D electromagnetic head 32 are closed. Among them, the energy regulation electromagnetic reversing valve 2 and the internal volume ratio regulation electromagnetic reversing valve 3 are selected to be connected to the oil cylinder body 1 through an external oil pipeline. The A solenoid valve 4 and the B solenoid valve 5 are selected to be directly connected to the oil cylinder body 1.

Claims

1. A screw compressor with a four-solenoid valve for automatically and steplessly adjusting the internal volume ratio efficiently. The inner cavity of the oil cylinder body (1) is separated into an energy regulation piston cavity and an internal volume ratio regulation piston cavity by an intermediate partition plate (7). The energy regulation piston cavity is separated into chamber a and chamber b by an energy regulation piston (6). The internal volume ratio regulation piston cavity is separated into chamber c and chamber d by an internal volume ratio piston (8). The energy regulation piston (6) is connected to an energy regulation slide valve (12) through an energy regulation guide rod (9). The internal volume ratio piston (8) is connected to an internal volume ratio slide valve (11) through an internal volume ratio guide rod (10). An energy regulation electromagnetic reversing valve (2) and an internal volume ratio regulation electromagnetic reversing valve (3) are connected to the oil cylinder body (1). An A electromagnetic head (21) controls the communication between chamber a and the oil supply passage, and the communication between chamber b and the oil return passage. A B electromagnetic head (22) controls the communication between chamber a and the oil return passage, and the communication between chamber b and the oil supply passage. A C electromagnetic head (31) controls the communication between chamber c and the oil supply passage, and the communication between chamber d and the oil return passage. A D electromagnetic head (32) controls the communication between chamber c and the oil return passage, and the communication between chamber d and the oil supply passage. It is characterized in that: Connected to both ends of a solenoid valve (4) through external oil pipelines are a chamber and a b chamber, and connected to both ends of a B solenoid valve (5) through external oil pipelines are a c chamber and a d chamber.

2. The screw compressor for automatically and steplessly and efficiently adjusting the content volume ratio with four solenoid valves according to claim 1, wherein: The energy regulating electromagnetic directional control valve (2) and the internal volume ratio regulating electromagnetic directional control valve (3) are selected to connect the external oil pipeline to the oil cylinder body (1).

3. A screw compressor for automatically and steplessly and efficiently adjusting the content volume ratio with four solenoid valves according to claim 1, characterized in that: The A solenoid valve (4) and the B solenoid valve (5) are directly connected to the oil cylinder body (1).

4. A control method for a screw compressor that automatically and steplessly adjusts the internal volume ratio efficiently with four solenoid valves as described in claim 1, characterized in that: When the internal volume ratio increases, open the C electromagnetic head (31) and the A solenoid valve (4); when the internal volume ratio decreases, open the B electromagnetic head (22) and the B solenoid valve (5); when the internal volume ratio reaches the specified position, close the four solenoid valves, namely the energy regulating electromagnetic directional control valve (2), the internal volume ratio regulating electromagnetic directional control valve (3), the A solenoid valve (4), and the B solenoid valve (5), and close the A electromagnetic head (21), the B electromagnetic head (22), the C electromagnetic head (31), and the D electromagnetic head (32).

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