A screw compressor unloading device, a screw compressor unloading control method and a screw compressor

Abstract

The present application provides a screw compressor's loading and unloading device, a loading and unloading control method and a screw compressor. The screw compressor's loading and unloading device has: a hydraulic cylinder including a cylinder body and a piston reciprocating in the cylinder body; an oil inlet path connected to the hydraulic cylinder and kept in a constant open state; and an oil outlet path connected to the hydraulic cylinder, wherein an oil discharge valve for closing the oil outlet path is arranged in the oil outlet path, and the supply amount of hydraulic fluid flowing from the oil inlet path per unit time is less than the discharge amount of the hydraulic fluid flowing from the oil outlet path per unit time in the loading process and the unloading process.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of compressors, in particular to a screw compressor loading and unloading device, a screw compressor loading and unloading control method, and a screw compressor. BACKGROUND

[0002] The screw compressor usually adopts the reciprocating movement of a slide valve and a piston to realize capacity regulation or pressure ratio regulation, and the reciprocating movement of the slide valve and the piston is realized by the suction and discharge of hydraulic fluid in the oil cylinder through an oil circuit to realize the loading and unloading regulation of the compressor.

[0003] However, in the existing loading and unloading process of the screw compressor, it is necessary to control the opening and closing of the 100% loading solenoid valve, that is, at least one of the 100% loading solenoid valve and the unloading solenoid valve corresponding to each volume percentage needs to be controlled to realize loading and unloading, whether in the loading process or in the unloading process. Therefore, the logic of the combined loading and unloading process is relatively complex.

[0004] Therefore, it is urgent to develop a technology capable of simplifying the control logic in the loading and unloading process of the screw compressor. SUMMARY

[0005] To solve the above-mentioned problems, the present application provides a screw compressor loading and unloading device, a screw compressor loading and unloading control method capable of simplifying the control logic in the loading and unloading process of the screw compressor, and a screw compressor provided with the above-mentioned loading and unloading device.

[0006] Solution for solving the problem

[0007] A technical solution of the present application is a screw compressor loading and unloading device, characterized in that,

[0008] The screw compressor loading and unloading device comprises:

[0009] a hydraulic cylinder comprising a cylinder body and a piston reciprocating in the cylinder body;

[0010] an oil inlet circuit connected to the hydraulic cylinder and kept in a constant open state; and

[0011] an oil outlet circuit connected to the hydraulic cylinder, wherein an oil discharge valve for closing the oil outlet circuit is arranged in the oil outlet circuit,

[0012] In the loading process and the unloading process, the supply amount of the hydraulic fluid flowing from the oil inlet circuit per unit time is less than the discharge amount of the hydraulic fluid flowing from the oil outlet circuit per unit time.

[0013] According to the technical scheme, compared with the prior art, during the loading and unloading process, especially during the switching of loading and unloading, the switch of the 100% loading electromagnetic valve arranged on the oil inlet pipe does not need to be switched, and only one corresponding unloading valve needs to be controlled. Therefore, from the structure, since the loading electromagnetic valve is cancelled, the structure of the loading and unloading device of the screw compressor is simplified, and the cost of the device is reduced.

[0014] In addition, preferably, a throttling mechanism is arranged in the oil inlet path.

[0015] According to the technical scheme, by arranging the throttling mechanism in the oil inlet path, the supply amount of the hydraulic fluid per unit time can be less than the discharge amount per unit time, so that dynamic balance control can be simply realized. Moreover, accurate control of the loading and unloading time can be realized.

[0016] In addition, preferably, a throttling mechanism is arranged in the oil inlet path.

[0017] According to the technical scheme, by arranging the throttling mechanism in the oil inlet path, the supply amount of the hydraulic fluid per unit time can be less than the discharge amount per unit time, so that dynamic balance control can be simply realized. Moreover, accurate control of the loading and unloading time can be realized.

[0018] In addition, preferably, the aperture of the oil inlet path is smaller than the aperture of the oil outlet path.

[0019] According to the technical scheme, by making the aperture of the oil inlet path smaller than the aperture of the oil outlet path, the supply amount of the hydraulic fluid per unit time can be less than the discharge amount per unit time, so that dynamic balance control can be simply realized.

[0020] In addition, preferably, the ratio of the supply amount of the hydraulic fluid per unit time flowing from the oil inlet path to the discharge amount of the hydraulic fluid per unit time flowing from the oil outlet path is less than or equal to 4 / 5.

[0021] According to the technical scheme, the efficiency of the loading and unloading device of the screw compressor can be improved.

[0022] In addition, preferably, the hydraulic fluid is hydraulic oil.

[0023] According to the technical scheme, by making the hydraulic fluid hydraulic oil, the working efficiency and cost of the hydraulic cylinder can be considered.

[0024] In addition, preferably, the oil unloading valve is an electromagnetic valve.

[0025] According to the technical scheme, by making the oil unloading valve an electromagnetic valve, the loading and unloading time can be controlled, and the convenience of control is improved.

[0026] Further, preferably, the throttling mechanism is at least one of a throttle hole, a throttle valve, and a capillary tube.

[0027] According to the technical solution, the hydraulic fluid flow can be adjusted, and thus the precise control of the loading and unloading time can be realized. Moreover, the cost can be saved according to appropriate selection of the inventory.

[0028] Further, preferably, the number of the oil discharge paths is multiple.

[0029] According to the technical solution, by making the number of the oil discharge paths multiple, the volume ratio during the loading and unloading process can be more finely controlled.

[0030] Further, preferably, the diameters of the multiple oil discharge paths are the same.

[0031] According to the technical solution, by making the diameters of the multiple oil discharge paths the same, the interchangeability can be improved, the cost can be reduced, and the production is facilitated.

[0032] Further, preferably, the lengths of the multiple oil discharge paths are the same.

[0033] According to the technical solution, by making the lengths of the multiple oil discharge paths the same, the interchangeability can be improved, the cost can be reduced, and the production is facilitated.

[0034] Another technical solution of the application is a loading and unloading control method of a screw compressor, characterized in that,

[0035] The loading and unloading control method of the screw compressor comprises the following procedures:

[0036] The oil inlet path connected to the hydraulic cylinder of the screw compressor is kept always open, so that the hydraulic fluid always flows into the hydraulic cylinder during the loading and unloading process;

[0037] During the loading process, the oil discharge valve provided on the oil discharge path located at the immediately downstream side of the piston in the moving direction is opened, the oil discharge valve provided on the oil discharge path located at the immediately upstream side of the piston in the moving direction is closed, and the supply amount of the hydraulic fluid flowing from the oil inlet path per unit time is less than the discharge amount of the hydraulic fluid flowing from the oil discharge path per unit time, so that the piston moves from the immediately upstream side of the oil discharge path to the immediately downstream side of the oil discharge path and stays at the immediately downstream side of the oil discharge path; and

[0038] During unloading, an unloading valve provided on the oil discharge path on the immediately downstream side of the movement direction of the piston is opened, an unloading valve provided on the oil discharge path on the immediately upstream side of the movement direction of the piston is closed, and the supply amount per unit time of the hydraulic fluid flowing in from the oil inlet path is made smaller than the discharge amount per unit time of the hydraulic fluid flowing out from the oil discharge path, thereby moving the piston from the immediately upstream side of the oil discharge path to the immediately downstream side of the oil discharge path and stopping at the immediately downstream side of the oil discharge path.

[0039] According to the technical solution, compared with the prior art, during loading and unloading, especially during switching of loading and unloading, the switch of the 100% loading electromagnetic valve provided on the oil inlet pipe does not need to be switched, and only the corresponding unloading valve needs to be controlled. Therefore, from the control logic, the control logic of the loading and unloading of the screw compressor can be effectively simplified, the operation of the screw compressor set is simpler, errors are less likely to occur, and the operation cost of the logic control can be reduced.

[0040] In addition, preferably, the oil inlet path is throttled.

[0041] According to the technical solution, by throttling the oil inlet path, the supply amount per unit time of the hydraulic fluid can be made smaller than the discharge amount per unit time, thereby simply achieving dynamic balance control. Moreover, accurate control of the loading and unloading time can be achieved.

[0042] In addition, preferably, the oil inlet path and the oil discharge path are both throttled.

[0043] According to the technical solution, by throttling the oil inlet path and the oil discharge path, the supply amount per unit time of the hydraulic fluid can be made smaller than the discharge amount per unit time, thereby simply achieving dynamic balance control. Moreover, accurate control of the loading and unloading time can be further achieved.

[0044] In addition, preferably, the ratio of the supply amount per unit time of the hydraulic fluid flowing in from the oil inlet path to the discharge amount per unit time of the hydraulic fluid flowing out from the oil discharge path is less than or equal to 4 / 5.

[0045] According to the technical solution, the efficiency of the loading and unloading device of the screw compressor can be improved.

[0046] Still another technical solution of the present application is a screw compressor, characterized in that the screw compressor is provided with the loading and unloading device of the screw compressor according to any one of the technical solutions.

[0047] According to the technical solution, since the loading and unloading device according to any one of the technical solutions is provided, the screw compressor of the technical solution has the advantages of the loading and unloading device according to any one of the technical solutions.

[0048] Effects of the Invention

[0049] According to the present application, a screw compressor unloading device, a screw compressor unloading control method, and a screw compressor provided with the above-mentioned unloading device can effectively simplify the control logic of the screw compressor unloading, make the screw compressor unit operation more simple and less prone to errors, and reduce the operating cost of the logic control. In addition, by setting a throttling mechanism on the loading oil circuit and / or the unloading oil circuit, the precise control of the unloading time can be further achieved. BRIEF DESCRIPTION OF DRAWINGS

[0050] Figure 1 is a schematic diagram of the unloading device of the screw compressor of embodiment 1 of the present application when the 50% unloading valve is used for loading adjustment.

[0051] Figure 2 is a schematic diagram of the unloading device of the screw compressor of embodiment 1 of the present application when the 50% unloading valve is used for unloading adjustment.

[0052] Figure 3 is a schematic diagram of the unloading device of the screw compressor of embodiment 2 of the present application when the 50% unloading valve is used for loading adjustment.

[0053] Figure 4 is a schematic diagram of the unloading device of the screw compressor of embodiment 2 of the present application when the 50% unloading valve is used for unloading adjustment.

[0054] Figure 5 is a schematic diagram of the unloading device of the screw compressor of embodiment 3 of the present application when the 50% unloading valve is used for loading adjustment.

[0055] Figure 6 is a schematic diagram of the unloading device of the screw compressor of embodiment 3 of the present application when the 50% unloading valve is used for unloading adjustment. DETAILED DESCRIPTION

[0056] Hereinafter, the embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments are not intended to limit the technical scope of the present application. Although a plurality of features are described in the embodiments, the plurality of features are not intended to limit the features of the technical scope of the present application, and the plurality of features can be arbitrarily combined. In addition, in the drawings, the same or similar structures are denoted by the same reference numerals, and repetitive description is omitted.

[0057] As used in the specification, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. As used in the specification and in the claims, the term "comprising" and variations thereof (e.g., "comprise", "comprises", "including", "includes", "include") mean "including but not limited to" and is not intended to (and does not) exclude other moieties, additives, components, integers or steps.

[0058] In the specification, when it is said that an element is "on", "attached" to, "connected" to, "coupled" to, or "contacting" another element, it can be directly on, attached to, connected to, coupled to, or contacting the other element, or one or more intervening elements can also be present.

[0059] In the specification, the terms "first", "second", "third", etc. are used only to facilitate the description and are not intended to limit.

[0060] In the specification, spatially relative terms such as "upper", "lower", "front", "back", "top", "bottom" and the like can be used for describing the relationship between an element and another element as illustrated in the drawings. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the drawings. For example, if a device is turned over in the drawings, a feature that is described as "below" or "beneath" another feature would then be oriented "above" or "over" the other feature. The device can be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors will be interpreted accordingly.

[0061] Figure 1 is a schematic view of the load-unload device of the screw compressor of Embodiment 1 of the present application when the load adjustment is performed with the 50% unload valve. Figure 2 is a schematic view of the load-unload device of the screw compressor of Embodiment 1 of the present application when the unload adjustment is performed with the 50% unload valve. Figure 3 is a schematic view of the load-unload device of the screw compressor of Embodiment 2 of the present application when the load adjustment is performed with the 50% unload valve. Figure 4 is a schematic view of the load-unload device of the screw compressor of Embodiment 2 of the present application when the unload adjustment is performed with the 50% unload valve. Figure 5 is a schematic view of the load-unload device of the screw compressor of Embodiment 3 of the present application when the load adjustment is performed with the 50% unload valve. Figure 6 is a schematic view of the load-unload device of the screw compressor of Embodiment 6 of the present application when the unload adjustment is performed with the 50% unload valve. Embodiment 1

[0062] AsFigure 1 and Figure 2 As shown in FIG. 1, the screw compressor unloading device 100 of the present application is provided with a hydraulic cylinder 10, an oil inlet pipe E, oil outlet pipes P1, P2, P3, and oil discharge valves D1, D2, D3 respectively arranged in the oil outlet pipes P1, P2, P3.

[0063] Specifically, the hydraulic cylinder 10 is composed of a cylinder body 20 and a piston 30, an oil inlet port 24 is formed on the side of the cylinder body 20 facing the piston 30, an oil inlet pipe E (always open) is installed on the oil inlet port 24, oil outlet ports 21, 22, 23 are respectively formed on the side of the cylinder body 20 adjacent to the side on which the oil inlet port 24 is located, and oil outlet pipes P1, P2, P3 are respectively installed on the oil outlet ports 21, 22, 23. In addition, oil discharge valves D1, D2, D3 for controlling the cutoff or conduction of the oil outlet pipes P1, P2, P3 are respectively installed on the oil outlet pipes P1, P2, P3.

[0064] Figure 1 FIG. 1 is a schematic diagram of the screw compressor unloading device of Example 1 of the present application when the 50% unloading valve is adjusted for loading. In Figure 1 , the oil outlet ports 21, 22, 23 are the oil outlet ports for 25% load, 50% load, and 75% load in order, and correspondingly, the oil outlet pipes P1, P2, P3 are the oil outlet pipes for 25% load, 50% load, and 75% load in order, and the oil discharge valves D1, D2, D3 are the unloading valves for 25% load, 50% load, and 75% load in order. In the present application, these unloading valves are also referred to as 25% unloading valve, 50% unloading valve, and 75% unloading valve.

[0065] Hereinafter, the process of increasing the load of the screw compressor is referred to as the loading process, for example, increasing from 25% load to 50% load, and the process of reducing the load of the screw compressor is referred to as the unloading process, for example, reducing from 75% load to 50% load.

[0066] As Figure 1As shown, during the loading process, when the load of the screw compressor is to be increased from 25% load to 50% load, the 25% unload valve (oil discharge valve D1) is closed and the 50% unload valve (oil discharge valve D2) is opened by means of a control device not shown. At this time, since the oil inlet pipe E installed at the oil inlet 24 is set to be always open, the loading oil circuit becomes a constant oil passage. At this time, the hydraulic fluid in the compressor is driven by the differential pressure F1 between both ends to enter the hydraulic cylinder 10 at the rightmost position in the drawing at a supply flow rate Q1, and further drive the piston 30 to run from the 25% unload valve oil circuit (oil discharge port 21) to the left in the drawing. When the piston 30 moves to the 50% unload valve oil circuit (oil discharge port 22), the hydraulic fluid in the hydraulic cylinder 10 is discharged from the 50% unload valve oil circuit (oil discharge port 22) to the outside of the hydraulic cylinder 10 at a discharge flow rate Q2. Here, the supply flow rate Q1 and the discharge flow rate Q2 both refer to the flow rate per unit time.

[0067] At this time, if the supply flow rate Q1 > the discharge flow rate Q2, the piston 30 will continue to load, which cannot realize the regulation function of the 50% unload valve (oil discharge valve D2). Therefore, it is necessary to set Q1 < Q2, i.e., the supply flow rate is less than the discharge flow rate. Therefore, the piston 30 can be stably positioned at the 50% unload valve oil circuit (oil discharge port 22), so as to realize dynamic balance.

[0068] Similarly, in the case that the load of the screw compressor is increased from 0 to 25% load, and from 50% load to 75% load, etc., the same as the case that the load of the screw compressor is increased from 25% load to 50% load, which will not be described here.

[0069] In addition, Figure 2 is a schematic view of the loading and unloading device of the screw compressor of embodiment 1 of the present application when the 50% unload valve is used for unloading regulation. As shown, Figure 2 During the unloading process, when the load of the screw compressor is to be decreased from 75% load to 50% load, the 75% unload valve (oil discharge valve D3) is closed and the 50% unload valve (oil discharge valve D2) is opened by means of a control device not shown. At this time, since the oil inlet pipe E installed at the oil inlet 24 is set to be always open, the loading oil circuit becomes a constant oil passage. At this time, the piston 30 drives the hydraulic fluid (not shown) to run to the right from the position shown in the drawing under the action of the differential pressure F2 between both ends. At this time, the hydraulic cylinder 10 simultaneously has the supply flow rate Q1 and the discharge flow rate Q2. The size relationship between the supply flow rate Q1 and the discharge flow rate Q2 is set to be Q1 < Q2, i.e., the supply flow rate is less than the discharge flow rate. In this case, the piston 30 will continue to run to the 50% unload valve oil circuit (oil discharge port 22). When the oil piston approaches the 50% unload valve oil circuit (oil discharge port 22) and gradually blocks the oil discharge port 22, Q2 will become smaller. When Q1 = Q2, the supply flow rate is equal to the discharge flow rate, and the oil piston will stay at this position, so as to realize dynamic balance.

[0070] Also, in the case where the load of the screw compressor is reduced from 100% load to 75% load, and from 50% load to 25% load, and the like, the same applies to the case where the load of the screw compressor is reduced from 75% load to 50% load, and the like, and thus the description thereof will not be repeated here.

[0071] In Embodiment 1, the unloading flow paths of 25% load, 50% load, and 75% load are provided, respectively, and of course, unloading flow paths of different percentages of load can be provided as needed. In addition, in order to control the volume ratio more finely, more stages of unloading flow paths can be provided.

[0072] Note that, in the present application, in the process of loading, for example, in the process of increasing from 25% load to 50% load, the unloading valve oil path of 50% load is referred to as the discharge oil path on the immediately downstream side in the moving direction of the piston, and the unloading valve oil path of 25% load is referred to as the discharge oil path on the immediately upstream side in the moving direction of the piston. Also, in the process of unloading, for example, in the process of reducing from 75% load to 50% load, the unloading valve oil path of 50% load is referred to as the discharge oil path on the immediately downstream side in the moving direction of the piston, and the unloading valve oil path of 75% load is referred to as the discharge oil path on the immediately upstream side in the moving direction of the piston.

[0073] Of course, the embodiments herein are merely examples, and the positions and numbers of the oil inlet ports and the oil discharge ports are not limited to the present application, and are not particularly limited as long as loading and unloading can be achieved.

[0074] In addition, in Embodiment 1, for the unloading valve, an electromagnetic valve is preferably used from the perspective of the convenience of control and the ability to control the loading and unloading time, and of course, the unloading valve is not limited to an electromagnetic valve.

[0075] In addition, the hydraulic fluid can use various fluids, and from the perspective of balancing work efficiency and cost, a hydraulic oil is preferably used. The grade thereof can be appropriately selected according to the specific scenario.

[0076] Note that, in the above-described Embodiment 1, in the process of loading and in the process of unloading, since the oil inlet pipe E installed at the oil inlet port 24 is set to be always open, i.e., there is no on-off valve for opening and closing the oil inlet pipe E, the loading oil path becomes a constant-through oil path.

[0077] In this way, compared with the prior art, in the process of loading and unloading, and in particular, in the switching of loading and unloading, it is not necessary to switch the on-off of the 100% loading electromagnetic valve provided at the oil inlet pipe, and only one corresponding unloading valve needs to be controlled.

[0078] In the embodiment 1, the size relationship of the supply amount Q1 and the discharge amount Q2 is set as Q1 < Q2, that is, the supply amount is less than the discharge amount. In other words, as long as the supply amount can be ensured to be less than the discharge amount, the above simple control can be realized in the state that the loading oil path becomes a constant-through oil path.

[0079] In the embodiment 1, in order to realize Q1 < Q2, it can be realized by making the aperture of the loading oil path smaller than the aperture of the unloading oil path, it can also be realized by setting a throttling mechanism on the loading oil path to make the supply amount smaller, and it can also be realized by setting throttling mechanisms on the loading oil path and the unloading oil path at the same time, and making the supply amount smaller through the different throttling effects of the throttling mechanisms.

[0080] According to the loading and unloading device of the screw compressor of the embodiment 1, from the structure, since the loading electromagnetic valve is cancelled, the structure of the loading and unloading device of the screw compressor is simplified, and the device cost is reduced. In addition, from the control logic, as shown in Table 1, the control logic of the loading and unloading of the screw compressor can be effectively simplified, the operation of the screw compressor set is simpler, and it is not easy to make mistakes, and the operation cost of the logic control can also be reduced.

[0081] Table 1

[0082] Embodiment 2

[0083] As shown in Figure 3 and Figure 4 , in the embodiment 2, the loading and unloading device 200 of the screw compressor of the present application is provided with a throttling mechanism in the oil inlet pipe, and in addition, it is the same as the embodiment 1, and only the different parts from the embodiment 1 will be described below.

[0084] Specifically, as shown in Figure 3 and Figure 4 , a throttling plate hole EM is provided in the oil inlet pipe E. By providing a throttling mechanism in the oil inlet pipe, the input oil amount is made smaller, and Q1 < Q2 is realized.

[0085] Of course, the throttling mechanism is not limited to the throttling plate hole in the embodiment, but can also be a throttling valve, a capillary tube and other components with throttling effect. Therefore, the components in stock can be appropriately selected to save costs.

[0086] By designing a throttling mechanism on the loading oil path, the hydraulic fluid flow can be adjusted, and the precise control of the loading and unloading time can be realized. Embodiment 3

[0087] As shown in Figure 5 and Figure 6As shown in Embodiment 3, the unloading device 300 of the screw compressor of the present application is provided with throttle mechanisms in both the oil inlet pipe and the oil discharge pipe, and is the same as Embodiments 1 and 2 except for this, and only the different parts from Embodiments 1 and 2 will be described below.

[0088] Specifically, as shown in Figure 5 and Figure 6 two throttle holes EM are provided in the oil inlet pipe E, and one throttle hole P1M, P2M, P3M is provided in each of the oil discharge pipes P1, P2, P3, respectively.

[0089] In Embodiment 3, the hole diameters and lengths of each of the throttle holes EM and the throttle holes P1M, P2M, P3M are the same. In other words, by providing two throttle holes EM in the oil inlet pipe E, the length of the throttle hole is increased, and thus Q1 < Q2 is achieved.

[0090] In addition, instead of providing two throttle holes EM in the oil inlet pipe E with the same hole diameters and lengths, one throttle hole with a smaller hole diameter and / or a longer hole length than the throttle holes P1M, P2M, P3M can also be provided.

[0091] Of course, as mentioned above, the throttle mechanism is not limited to the throttle hole in this embodiment, and can also be a throttle valve, a capillary tube, or other components with throttling effect.

[0092] In addition, two different throttle mechanisms can also be provided in the oil inlet pipe E in Embodiment 3, as long as Q1 < Q2 can be achieved, and there is no particular limitation.

[0093] By designing respective throttle mechanisms on the unloading oil circuit, the hydraulic fluid flow is adjusted by changing the number, hole diameter, and opening of the throttle mechanism, and thus more accurate control of the unloading time can be achieved.

[0094] In order to unify the hole diameters and lengths of the oil circuit for ease of production, generally, Q1 < Q2 is achieved by increasing the throttle mechanism on the unloading oil circuit. For example, Q1 / Q2 ≤ 4 / 5 is required, and then the throttle mechanism is designed. Of course, Q1 / Q2 is not limited to ≤ 4 / 5, and can also be other ratios. From the efficiency of unloading, Q1 / Q2 ≤ 4 / 5 is preferred.

[0095] For example, as shown in Figure 5 and Figure 6As shown, throttling mechanisms are arranged on the loading oil path and the three unloading oil paths, mainly for adjusting the loading and unloading time t of the compressor, and the calculation formula is: t=m*(Q2-Q1) / F*A, wherein m and A are the mass and cross-sectional area of the piston 30 respectively. m and A are known values, the pressure difference F of the hydraulic fluid at both ends can be calculated through specific operating conditions, and t is determined according to the requirements of different equipment, in combination with the above Q1 / Q2≤4 / 5, the Q1 value and the Q2 value can be inversely calculated, so as to design the throttling mechanism.

[0096] The screw compressor of the present application has the above-mentioned loading and unloading device, and can be applied not only to refrigeration equipment such as air conditioners and refrigerators, but also to power systems of machines and automobiles.

[0097] Of course, the loading and unloading device and the loading and unloading control method of the screw compressor of the present application, and the screw compressor are not limited to the technical solutions described in the above embodiments, as long as they can effectively simplify the control logic of the loading and unloading of the screw compressor, reduce the operating cost of the logic control, and realize precise control of the loading and unloading time, various appropriate changes can also be made.

[0098] It should be noted that aspects of the present application described with respect to one embodiment can be included in other different embodiments, although not specifically described with respect to the other different embodiments. In other words, all embodiments and / or features of any embodiment can be combined in any manner and / or combination, as long as they are not mutually contradictory.

Claims

1. A loading and unloading device for a screw compressor, characterized in that, The screw compressor's loading and unloading device includes: A hydraulic cylinder includes a cylinder body and a piston that reciprocates within the cylinder body; The oil inlet passage, connected to the hydraulic cylinder, is kept in a normally open state; and An oil discharge passage is connected to the hydraulic cylinder, and an oil discharge valve is provided in the oil discharge passage for closing the oil discharge passage. The diameter of the inlet passage is smaller than the diameter of the outlet passage. During the loading and unloading processes, the supply of hydraulic fluid flowing into the inlet passage per unit time is less than the discharge of hydraulic fluid flowing out of the outlet passage per unit time.

2. The loading and unloading device for a screw compressor according to claim 1, characterized in that, A throttling mechanism is provided in the oil inlet passage.

3. The loading and unloading device for a screw compressor according to claim 1, characterized in that, Both the oil inlet and the oil outlet are equipped with throttling mechanisms.

4. The loading and unloading device for a screw compressor according to any one of claims 1 to 3, characterized in that, The ratio of the amount of hydraulic fluid supplied per unit time from the inlet to the amount of hydraulic fluid discharged per unit time from the outlet is less than or equal to 4 / 5.

5. The loading and unloading device for a screw compressor according to any one of claims 1 to 3, characterized in that, The hydraulic fluid is hydraulic oil.

6. The loading and unloading device for a screw compressor according to any one of claims 1 to 3, characterized in that, The unloading valve is a solenoid valve.

7. The loading and unloading device for a screw compressor according to claim 2 or 3, characterized in that, The throttling mechanism is at least one of a throttling plate orifice, a throttling valve, and a capillary tube.

8. The loading and unloading device for a screw compressor according to any one of claims 1 to 3, characterized in that, There are multiple oil drain lines.

9. The loading and unloading device for a screw compressor according to claim 8, characterized in that, The orifices of multiple oil drain passages are the same.

10. The loading and unloading device for a screw compressor according to claim 9, characterized in that, The lengths of all of the oil drain lines are the same.

11. A method for loading and unloading control of a screw compressor, characterized in that, The loading and unloading control method for the screw compressor includes the following steps: The oil inlet passage of the hydraulic cylinder connected to the screw compressor is kept open, so that hydraulic fluid always flows into the hydraulic cylinder during the loading and unloading process; During loading, the unloading valve on the drain line located immediately downstream of the piston in the direction of movement of the hydraulic cylinder is opened, and the unloading valve on the drain line located immediately upstream of the piston in the direction of movement of the piston is closed. The supply of hydraulic fluid flowing into the inlet is made less than the discharge of hydraulic fluid flowing out of the drain line per unit time, thereby causing the piston to move from the drain line immediately upstream to the drain line immediately downstream and stop at the drain line immediately downstream. as well as During the unloading process, the unloading valve located on the downstream side of the piston's movement direction is opened, the unloading valve located on the upstream side of the piston's movement direction is closed, and the supply of hydraulic fluid flowing into the inlet is made less than the discharge of hydraulic fluid flowing out of the outlet, thereby causing the piston to move from the upstream outlet to the downstream outlet and stop at the downstream outlet. The diameter of the oil inlet passage is smaller than the diameter of the oil outlet passage.

12. The loading and unloading control method for a screw compressor according to claim 11, characterized in that, The oil inlet path is throttled.

13. The loading and unloading control method for a screw compressor according to claim 11, characterized in that, Both the oil inlet and the oil outlet are throttled.

14. The loading and unloading control method for a screw compressor according to any one of claims 11 to 13, characterized in that, The ratio of the amount of hydraulic fluid supplied per unit time from the inlet to the amount of hydraulic fluid discharged per unit time from the outlet is less than or equal to 4 / 5.

15. A screw compressor, characterized in that, The screw compressor includes the loading and unloading device of the screw compressor according to any one of claims 1 to 10.

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