A screw compressor sliding valve mechanism and its working process

Abstract

The present invention relates to a screw compressor sliding valve mechanism and its working process. At present, the structure for limiting the sliding valve is relatively complex and difficult to process in practice. The present invention includes a sliding valve, a sliding valve rod and a piston. The sliding valve is installed in the sliding valve cavity of the screw compressor body. The present invention is characterized in that: it also includes a sliding valve positioning key and a sliding valve tray. The bottom of the sliding valve is provided with a keyway, and the keyway is arranged along the axial direction of the sliding valve. The end face of the screw compressor body is provided with a notch for accommodating the sliding valve positioning key, and the notch is connected to the sliding valve cavity. The top of the sliding valve positioning key is provided with a guide limiting strip, and the sliding valve positioning key is placed in the notch of the screw compressor body. The guide limiting strip on the sliding valve positioning key cooperates with the keyway on the sliding valve; the sliding valve tray is fixed on the end face of the screw compressor body, and the sliding valve tray supports the outer end face of the sliding valve positioning key, and the sliding valve tray cooperates with the sliding valve. The present invention has a simple structure, reasonable design, and high matching accuracy.

Description

Technical Field

[0001] The invention relates to a screw compressor sliding valve mechanism and a working process thereof, and belongs to a component of a screw compressor. Background Art

[0002] In practical applications, screw compressors sometimes need to have the function of capacity regulation or pressure ratio regulation. When the compressor is driven by a fixed speed driver (such as a fixed frequency motor), the capacity regulation slide valve can be used to shorten the effective coating length of the rotor cavity to adjust the compressor volume flow. When the compressor needs to adjust the pressure ratio / content volume ratio, the content volume ratio adjustment slide valve can be used to change the exhaust time node of the exhaust orifice by moving the slide valve to adjust the compressor content volume ratio.

[0003] For machining process considerations, it is preferred that the slide valve and the slide valve cavity be made into a cylindrical cross-section. Therefore, the contact surface between the slide valve and the slide valve cavity is a positive cylindrical rotating surface. However, this structure requires a locating key to prevent the slide valve from deflecting along the cylindrical axis in the slide valve cavity. This locating key is usually axially limited and fastened by a screw, and the left and right limits of the locating key are guaranteed by the width tolerance between the locating key slot and the locating key. Figure 1 At present, the structure for limiting the position of the slide valve is relatively complex, the actual processing is difficult, and it involves multiple main structural parts with poor matching accuracy.

[0004] like Figure 1In the prior art shown, the positioning key is axially limited and fastened by a screw. In the actual production process, it is well known to those skilled in the art that the assembly between the screw and the positioning key is a clearance fit, and interference fit cannot be used, otherwise the positioning key cannot be installed in the actual production process. It is because the assembly between the screw and the positioning key is a clearance fit, which leads to a small gap between the positioning key and the moving key (this is a small gap caused by the clearance fit, and the gap is very small). The small gap caused by the assembly relationship of the clearance fit is very common in the mechanical field. The impact of this small gap on the quality of mechanical equipment in other industries is negligible, but for high-pressure equipment used to compress gas, such a small gap is enough to greatly reduce the performance and quality of the equipment. In the compressor, it is precisely because of the small gap between the positioning key and the moving key that the sliding valve also has a small gap between the moving key and the moving key. If there is no gap between the sliding valve and the rotor, or the gap is very small, the sliding valve will be affected by the gas force in the sliding valve cavity of the body and will move in the direction of the rotor. When the sliding valve touches the rotor, it will cause scratches or even jams. Therefore, in order to avoid the sliding valve's missing circle from scratching the moving (rotating) rotor, the gap between the sliding valve's missing circle and the rotor is usually increased to avoid scratching. However, since the sliding valve is on the high-pressure side of the compression process, increasing the gap here, although the gap is small, is after all a high-pressure compressed gas, it is difficult to achieve a good sealing effect, and the compressed gas will cause a large leakage. In order to solve the above problems, compressor manufacturers continuously optimize the tooth shape to reduce the leakage triangle area and contact line length to reduce the leakage of compressed gas, which greatly increases the structural complexity of the compressor. However, the leakage of high-pressure gas caused by the gap here is still large. After all, the high-pressure gas inside the compressor is much higher than the atmospheric pressure.

[0005] In short, in the prior art, under the premise of ensuring a good positioning function for the slide valve, even if a complex structure is adopted, it is impossible to achieve a good sealing effect between the notch of the slide valve and the rotor, which is a technical problem that people have been eager to solve but have never succeeded in solving. That is to say, in the prior art, under the premise of ensuring a good positioning function for the slide valve, no matter whether a simple structural improvement or a complex structural improvement is adopted, it is impossible to achieve a good sealing effect between the notch of the slide valve and the rotor. Summary of the invention

[0006] The purpose of the present invention is to overcome the above-mentioned deficiencies in the prior art and to provide a screw compressor sliding valve mechanism and its working process which has a simple structure, reasonable design, high matching accuracy and can effectively limit the sliding valve.

[0007] The technical solution adopted by the present invention to solve the above-mentioned problem is: the screw compressor sliding valve mechanism includes a sliding valve, a sliding valve rod and a piston, the two ends of the sliding valve rod are respectively connected to the sliding valve and the piston, and the sliding valve is installed in the sliding valve cavity of the screw compressor body. Its structural characteristics are: it also includes a sliding valve positioning key and a sliding valve tray, the bottom of the sliding valve is provided with a keyway, and the keyway is arranged along the axial direction of the sliding valve, the end surface of the screw compressor body is provided with a notch for accommodating the sliding valve positioning key, the notch is connected to the sliding valve cavity of the screw compressor body, the top of the sliding valve positioning key is provided with a guide limit strip for guiding and limiting the sliding valve, the sliding valve positioning key is placed in the notch of the screw compressor body, and the guide limit strip on the sliding valve positioning key cooperates with the keyway on the sliding valve; the sliding valve tray is fixed to the end surface of the screw compressor body, the sliding valve tray supports the outer end surface of the sliding valve positioning key, and the sliding valve tray cooperates with the sliding valve.

[0008] Preferably, the sliding valve tray of the present invention is fixed to the end surface of the screw compressor body by screws.

[0009] Preferably, the number of the keyway on the sliding valve of the present invention is one.

[0010] A working process of a sliding valve mechanism of a screw compressor is as follows: when pressure acts on a piston, the piston drives a sliding valve rod to control the movement of the sliding valve; when the sliding valve moves, the position of the sliding valve changes, thereby changing the effective working section length of the rotor, thereby changing the exhaust volume of the screw compressor; or changing the position of the exhaust port, thereby changing the internal volume ratio of the screw compressor; its characteristics are: the sliding valve positioning key is directly embedded in a notch located on the end face of the screw compressor body for accommodating the sliding valve positioning key, and the sliding valve positioning key has a total of six degrees of freedom, among which four degrees of freedom of the sliding valve positioning key are precisely positioned by the notch on the end face of the screw compressor body, the remaining one degree of freedom of the sliding valve positioning key is precisely positioned by the sliding valve tray, and the remaining other degree of freedom of the sliding valve positioning key is precisely positioned by the sliding valve, so that the six degrees of freedom of the sliding valve positioning key are all precisely constrained, thereby guiding the sliding valve.

[0011] Preferably, when the present invention is in operation, the keyway space at the bottom of the slide valve is at suction pressure (low pressure), so that the combined force of the gas always presses the slide valve tightly in the slide valve cavity, and the slide valve does not move in the direction of the rotor. Ensure that the gap between the missing circle of the slide valve and the rotor is as small as possible, thereby greatly reducing or even avoiding the leakage of high-pressure gas here, and improving the volumetric efficiency and isentropic efficiency during the compression process.

[0012] As a preferred embodiment, when the present invention is in operation, the slide valve positioning key is installed in a floating manner in the notch for accommodating the slide valve positioning key on the end face of the screw compressor body, the top of the slide valve positioning key is in the keyway of the slide valve, the floating range of the slide valve positioning key is extremely small, the floating range is used to reduce the friction between the slide valve positioning key and the keyway of the slide valve, and the extremely small floating range is designed to reduce the friction. The specific numerical range of this extremely small floating range is clear to those skilled in the art. The slide valve positioning key is not completely fixed and pressed by the slide valve, and has a certain floating space. In the actual operation process, it can float to a certain extent (of course, this floating range is very small, far less than the value of the clearance fit between the screw and the positioning key in the prior art) to reduce the friction between the slide valve positioning key and the slide valve keyway, thereby increasing the reliability of the entire mechanism. It is worth noting that although the slide valve positioning key can float up and down, since the floating range of the slide valve positioning key can float up and down is extremely small, the six degrees of freedom of the slide valve positioning key are still accurately positioned, which is easy to understand for those skilled in the art.

[0013] Compared with the prior art, the present invention has the following advantages and effects: reasonable structural design, the sliding valve can be limited and guided by the sliding valve, the sliding valve positioning key and the sliding valve tray, the structure is extremely simple, no extra fasteners are required, and the six degrees of freedom of the sliding valve positioning key are all constrained, the structure is simple, and the performance is reliable. The high-pressure keyway space at the bottom of the sliding valve is eliminated, so that the gas force on the sliding valve always keeps the sliding valve pressed in the sliding valve cavity, and the sliding valve will not be lifted. The sliding valve tray is an extension of the sliding valve cavity, and when the sliding valve is withdrawn from the sliding valve cavity for a long distance, the sliding valve can still be supported.

[0014] After using the present invention, the keyway space at the bottom of the slide valve is at suction pressure (low pressure) due to the design, so that the gas force always presses the slide valve tightly in the slide valve cavity, and it is impossible to move toward the rotor. Therefore, mechanically, the gap between the missing circle of the slide valve and the rotor can be minimized as much as possible, thereby reducing gas leakage here and improving the volumetric efficiency and isentropic efficiency during the compression process. This structure is simple, and the body and the slide valve tray are processed separately during processing; no extra fasteners are required during assembly, and there is no need to adjust the installation gap of the slide valve locating key, so that the six degrees of freedom of the slide valve locating key can be constrained, thereby guiding the slide valve. The overall structure is simple and reliable. The slide valve locating key is not completely fixed and pressed in the keyway, and there is a certain floating space. During actual operation, it can float to a certain extent to reduce the friction between the slide valve locating key and the slide valve keyway, thereby increasing the reliability of the mechanism.

[0015] Although the structure of the present invention is extremely simple, it very cleverly solves the technical problem that people have been eager to solve but have never been successful, and overcomes the technical prejudice of those skilled in the art that they must use fasteners such as screws to axially limit and tighten the positioning key. In actual production and sales, the present invention improves the axial limiting structure of the sliding valve positioning key and uses an extremely simple improvement in the axial limiting structure to achieve a particularly good sealing effect between the missing circle of the sliding valve and the rotor. In real life, a technical solution that can achieve good technical effects through extremely simple structural improvements is easy to succeed in business; what's more, the present invention solves the technical problem that people have been eager to solve but have never been successful, and is more likely to succeed in business. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention and / or the technical solutions in the prior art, the drawings required for use in the embodiments and / or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 It is a structural schematic diagram of the prior art.

[0018] Figure 2 1 is a schematic diagram of the structure of the slide valve mechanism of the screw compressor in an embodiment of the present invention. In the figure, all the slide valves are located in the slide valve cavity of the screw compressor body.

[0019] Figure 3 2 is a schematic diagram of the structure of the sliding valve mechanism of the screw compressor in an embodiment of the present invention. In the figure, a part of the sliding valve is located outside the sliding valve cavity of the screw compressor body, and this part of the sliding valve is supported by the sliding valve tray.

[0020] Figure 4 It is a schematic diagram of the structure among the slide valve, the slide valve positioning key, the slide valve tray, the rotor and the screw compressor body in an embodiment of the present invention.

[0021] Figure 5 It is a three-dimensional structural schematic diagram of the sliding valve mechanism of the screw compressor in an embodiment of the present invention.

[0022] Figure 6 yes Figure 5 Schematic diagram of the structure after removing the slide valve.

[0023] Figure 7 It is an enlarged structural schematic diagram of the slide valve in an embodiment of the present invention.

[0024] In the figure: 1-sliding valve; 11-keyway; 12-missing circle; 2-sliding valve rod; 3-piston; 4-sliding valve positioning key; 41-guide limit strip; 5-sliding valve tray; 6-exhaust port; 7-rotor; 8-screw compressor body; 9-sliding valve cavity; 10-rotor cavity. DETAILED DESCRIPTION

[0025] The present invention will be further described in detail below with reference to the accompanying drawings and by way of examples. The following examples are intended to explain the present invention but the present invention is not limited to the following examples.

[0026] Example

[0027] See also Figures 2 to 7 The sliding valve mechanism of the screw compressor in this embodiment includes a sliding valve 1, a sliding valve rod 2, a piston 3, a sliding valve positioning key 4 and a sliding valve tray 5.

[0028] A slide valve chamber 9 and a rotor chamber 10 are provided in the screw compressor body 8 . The slide valve chamber 9 and the rotor chamber 10 are connected via an exhaust port 6 . The rotor 7 is installed in the rotor chamber 10 of the screw compressor body 8 .

[0029] The two ends of the sliding valve rod 2 in this embodiment are respectively connected to the sliding valve 1 and the piston 3, that is, one end of the sliding valve rod 2 is fixed to the sliding valve 1, and the other end of the sliding valve rod 2 is fixed to the piston 3. The main body of the sliding valve 1 is a cylindrical structure, and the sliding valve 1 is installed in the sliding valve cavity 9 of the screw compressor body 8. The bottom of the sliding valve 1 is provided with a key groove 11, and the key groove 11 is arranged along the axial direction of the sliding valve 1, and the number of the key groove 11 is one.

[0030] The end surface of the screw compressor body 8 in this embodiment is provided with a notch for accommodating the slide valve positioning key 4 . The notch is in the shape of a rectangular parallelepiped and is communicated with the slide valve cavity 9 of the screw compressor body 8 . The shape and size of the sliding valve positioning key 4 match the notch. The main body of the sliding valve positioning key 4 is also a rectangular parallelepiped. A guide limit strip 41 is provided on the top of the sliding valve positioning key 4. The guide limit strip 41 is used to guide and limit the sliding of the sliding valve 1. The sliding valve positioning key 4 is placed in the notch of the screw compressor body 8. The guide limit strip 41 on the sliding valve positioning key 4 cooperates with the key groove 11 on the sliding valve 1. The guide limit strip 41 is located in the key groove 11. The top surface of the sliding valve positioning key 4 contacts the bottom surface of the sliding valve 1. When the sliding valve 1 slides, the key groove 11 at the bottom of the sliding valve 1 slides along the guide limit strip 41 on the top of the sliding valve positioning key 4. The outer end surface of the sliding valve positioning key 4 is flush with the outer end surface of the screw compressor body 8, and the remaining four surfaces on the sliding valve positioning key 4 are respectively in contact with the corresponding four surfaces in the rectangular notch on the end surface of the screw compressor body 8.

[0031] The sliding valve tray 5 in this embodiment is fixed to the end surface of the screw compressor body 8 by screws, and the sliding valve tray 5 supports the outer end surface of the sliding valve positioning key 4, so that the six degrees of freedom of the sliding valve positioning key 4 are constrained, and the sliding of the sliding valve 1 is accurately limited by the guide limit strip 41 on the sliding valve positioning key 4. It can be seen that only the extremely simple structure of the sliding valve 1, the sliding valve positioning key 4 and the sliding valve tray 5 is required, and no redundant fasteners are required to achieve accurate control of the sliding of the sliding valve 1, and the structure is simple and reliable.

[0032] The sliding valve tray 5 and the sliding valve 1 in this embodiment cooperate with each other. When the sliding valve 1 is withdrawn from the sliding valve cavity 9 for a long distance, the part of the sliding valve 1 withdrawn from the sliding valve cavity 9 will be supported on the sliding valve tray 5, that is, the sliding valve 1 can still be supported, thereby improving the performance of the sliding valve 1.

[0033] The working process of the screw compressor slide valve mechanism in this embodiment is as follows: when pressure acts on the piston 3, the piston 3 drives the slide valve rod 2 to control the movement of the slide valve 1; when the slide valve 1 moves, the position of the slide valve 1 changes, thereby changing the effective working section length of the rotor 7, thereby changing the exhaust volume of the screw compressor; or changing the position of the exhaust port 6, thereby changing the internal volume ratio of the screw compressor. The slide valve positioning key 4 is directly embedded in the notch located on the end face of the screw compressor body 8 for accommodating the slide valve positioning key 4. The slide valve positioning key 4 has a total of six degrees of freedom, among which four degrees of freedom of the slide valve positioning key 4 are precisely positioned by the notch on the end face of the screw compressor body 8, the remaining one degree of freedom of the slide valve positioning key 4 is precisely positioned by the slide valve tray 5, and the remaining other degree of freedom of the slide valve positioning key 4 is precisely positioned by the slide valve 1, so that the six degrees of freedom of the slide valve positioning key 4 are all precisely constrained, thereby guiding the slide valve 1. The keyway 11 space at the bottom of the slide valve 1 is at the suction pressure (low pressure), so that the combined force of the gas always presses the slide valve 1 tightly in the slide valve cavity 9, and the slide valve 1 will not move in the direction of the rotor. Ensure that the gap between the missing circle 12 of the slide valve 1 and the rotor 7 is as small as possible, thereby greatly reducing or even avoiding the leakage of high-pressure gas here, and improving the volumetric efficiency and isentropic efficiency during the compression process.

[0034] In order to reduce the friction between the sliding valve locating key 4 and the keyway 11, the present invention can install the sliding valve locating key 4 in a floating manner in the notch on the end face of the screw compressor body 8 for accommodating the sliding valve locating key 4. The top of the sliding valve locating key 4 is in the keyway 11 of the sliding valve 1. The floating range of the sliding valve locating key 4 is extremely small. The floating range is used to reduce the friction between the sliding valve locating key 4 and the keyway 11 of the sliding valve 1, thereby increasing the overall reliability of the mechanism.

[0035] The slide valve positioning key 4 in this embodiment is limited by the screw compressor body 8 and the slide valve tray 5, thereby guiding the slide valve 1. Since the pressure in the key slot 11 space at the bottom of the slide valve 1 is approximately equal to the low pressure, the combined force of the gas forces on the slide valve 1 is directed downward and is always maintained, thereby pressing the slide valve 1 at the bottom of the slide valve cavity 9 without lifting. The high-pressure key slot space at the bottom of the slide valve 1 is eliminated, so that the gas force on the slide valve 1 always keeps the slide valve 1 pressed in the slide valve cavity 9.

[0036] In addition, it should be noted that the shapes and names of the parts and components of the specific embodiments described in this specification may be different, and the above content described in this specification is only an example of the structure of the present invention. All equivalent changes or simple changes made based on the structure, features and principles described in the patent concept of the present invention are included in the protection scope of the patent of the present invention. Technicians in the technical field of the present invention can make various modifications or supplements to the specific embodiments described or replace them in a similar manner, as long as they do not deviate from the structure of the present invention or exceed the scope defined by the claims, they should all fall within the protection scope of the present invention.

Claims

1. A sliding valve mechanism for a screw compressor, comprising a sliding valve (1), a sliding valve rod (2) and a piston (3), wherein two ends of the sliding valve rod (2) are respectively connected to the sliding valve (1) and the piston (3), and the sliding valve (1) is installed in a sliding valve cavity (9) of a screw compressor body (8), characterized in that: The invention also comprises a slide valve positioning key (4) and a slide valve tray (5), wherein a key groove (11) is arranged at the bottom of the slide valve (1), and the key groove (11) is arranged along the axial direction of the slide valve (1); a notch for accommodating the slide valve positioning key (4) is arranged at the end surface of the screw compressor body (8), and the notch is communicated with the slide valve cavity (9) of the screw compressor body (8); a guide limit strip (41) for guiding and limiting the slide valve (1) is arranged at the top of the slide valve positioning key (4); and the slide valve positioning key (4) is arranged at the bottom of the slide valve (1). In the notch of the screw compressor body (8), the guide limit strip (41) on the slide valve positioning key (4) and the keyway (11) on the slide valve (1) cooperate; the slide valve tray (5) is fixed to the end face of the screw compressor body (8), the slide valve tray (5) bears against the outer end face of the slide valve positioning key (4), and the slide valve tray (5) and the slide valve (1) cooperate; the slide valve tray (5) is fixed to the end face of the screw compressor body (8) by screws; the number of the keyway (11) on the slide valve (1) is one.

2. A working process of a sliding valve mechanism of a screw compressor as claimed in claim 1, wherein the working process is as follows: when pressure acts on a piston (3), the piston (3) drives the sliding valve rod (2) to control the movement of the sliding valve (1); when the sliding valve (1) moves, the position of the sliding valve (1) changes, thereby changing the effective working section length of the rotor (7), thereby changing the exhaust volume of the screw compressor; or changing the position of the exhaust port (6), thereby changing the internal volume ratio of the screw compressor; characterized in that: The slide valve positioning key (4) is directly embedded in a notch located on the end surface of the screw compressor body (8) for accommodating the slide valve positioning key (4). The slide valve positioning key (4) has a total of six degrees of freedom, wherein four degrees of freedom of the slide valve positioning key (4) are precisely positioned by the notch on the end surface of the screw compressor body (8), the remaining one degree of freedom of the slide valve positioning key (4) is precisely positioned by the slide valve tray (5), and the remaining other degree of freedom of the slide valve positioning key (4) is precisely positioned by the slide valve (1). The six degrees of freedom of the slide valve positioning key (4) are all precisely constrained, thereby guiding the slide valve (1).

3. The working process of the screw compressor sliding valve mechanism according to claim 2 is characterized in that: During operation, the keyway (11) space at the bottom of the slide valve (1) is under suction pressure, so that the combined force of the gas always presses the slide valve (1) tightly in the slide valve cavity (9), and the slide valve (1) will not move in the direction of the rotor.

4. The working process of the screw compressor sliding valve mechanism according to claim 2 is characterized in that: During operation, the slide valve positioning key (4) is installed in a floating manner in a notch on the end surface of the screw compressor body (8) for accommodating the slide valve positioning key (4), and the top of the slide valve positioning key (4) is in the keyway (11) of the slide valve (1). The floating range of the slide valve positioning key (4) is extremely small, and the floating range is used to reduce the friction between the slide valve positioning key (4) and the keyway (11) of the slide valve (1).

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