Over-compression elimination device and variable pitch screw vacuum pump

Abstract

The present invention discloses an over-compression elimination device and a variable pitch screw vacuum pump, comprising a valve body, a valve stem movably connected in the valve body; the valve body has an inlet and an outlet; a valve cover is installed on one side of the outlet of the valve body, one end of the valve stem is connected to the valve cover, and the other end of the valve stem extends along the axial direction of the valve body to the inlet side of the valve body; the inlet end of the valve body of the elimination device is connected to the pressure chamber of an external mechanism. The over-compression elimination device of the present invention keeps the valve stem and the valve body sealed at all times by a retaining member. When the pressure in the pump chamber connected thereto is over-pressured, the pressure of the compressed air offsets the restoring force of the retaining member to drive the valve stem to move, so as to achieve communication with the outside world, thereby achieving pressure relief. This structure effectively reduces the exhaust temperature and shaft power consumption of the variable pitch screw vacuum pump, and improves the operating efficiency, reliability and air extraction performance.

Description

Technical Field

[0001] The invention relates to the technical field of screw vacuum pumps, and in particular to an over-compression elimination device and a variable pitch screw vacuum pump having the same. Background Art

[0002] Compared with other vacuum pumps, the screw vacuum pump is a dry multi-stage vacuum pump. It will not pollute the vacuum system during operation, is low-carbon and environmentally friendly, can maintain a high pumping speed within a relatively wide pressure range, has a short gas channel in the pump, is easy to carry out anti-corrosion treatment, has a wide range of applications, and has been widely used in many fields.

[0003] Variable pitch screw vacuum pumps have internal compression characteristics in the process of transmitting gas. Compared with equal pitch screw vacuum pumps, they have high efficiency when operating under higher compression ratio conditions. Therefore, in recent years, variable pitch screw vacuum pumps have become upgraded products of equal pitch screw vacuum pumps. However, since variable pitch screw vacuum pumps have internal compression characteristics in the process of transmitting gas, and the compression ratio is fixed, they are suitable for long-term operation under conditions where the suction port pressure is relatively low (much less than the exhaust pressure). If they are operated under conditions where the inlet pressure is relatively high (close to the exhaust pressure), "over-compression phenomenon" will occur in the vacuum pump, causing the exhaust temperature to be too high, the shaft power to increase sharply, and the operating efficiency, reliability and exhaust performance of the pump to be seriously reduced. Since the inlet pressure working range of the screw vacuum pump is from atmospheric pressure (the exhaust pressure of the general screw vacuum pump) to far less than atmospheric pressure, the working pressure range is relatively wide. Therefore, when the variable pitch screw vacuum pump is operated under the condition of relatively high inlet pressure, over-compression will occur inside the screw vacuum pump. This over-compression phenomenon seriously affects the promotion and application of variable pitch screw vacuum pumps and their operating efficiency. Summary of the invention

[0004] The object of the present invention is to provide an over-compression elimination device and a variable pitch screw vacuum pump having the same, which can effectively reduce the exhaust temperature and shaft power consumption of a variable pitch screw vacuum pump and improve the operating efficiency, reliability and exhaust performance.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] The over-compression elimination device of the present invention comprises:

[0007] Valve body;

[0008] A valve stem movably connected to the valve body;

[0009] The valve body has an inlet and an outlet;

[0010] A valve cover is installed on the outlet side of the valve body, one end of the valve stem is connected to the valve cover, and the other end of the valve stem extends along the axial direction of the valve body to the inlet side of the valve body;

[0011] An inlet end of the valve body of the elimination device is communicated with a pressure chamber of an external mechanism;

[0012] The position where the valve body communicates with the pressure chamber is configured as a sealing surface;

[0013] The valve stem can extend to the sealing surface at one end close to the inlet to isolate the valve body from the pressure chamber of the external mechanism;

[0014] The valve body is integrated with a retaining member that holds the valve stem in the sealing surface to form a sealing structure.

[0015] Furthermore, the valve stem is configured in two states:

[0016] The first state is when the pressure in the pressure chamber of the external mechanism is not greater than the pressure at the outlet of the valve body, the valve stem contacts the sealing surface through the retaining member and forms a sealing structure to isolate the valve body and the pressure chamber;

[0017] In the second state, when the pressure in the pressure chamber of the external mechanism is greater than the pressure at the outlet of the valve body, the valve stem moves along the axial direction of the valve body toward the outlet side to move away from the sealing surface.

[0018] Furthermore, the retaining member is a spring.

[0019] Furthermore, the valve body is a hollow structure;

[0020] The valve cover comprises a valve cover body assembled with the valve body, and a valve cover mounting body formed at the axis of the valve cover body;

[0021] The lower portion of the valve stem is embedded in the valve cover mounting body to be assembled with the valve cover;

[0022] The valve cover body is provided with valve cover holes along its circumference.

[0023] Furthermore, one end of the retaining member is fixedly connected to the valve cover mounting body, and the other end of the retaining member is fixedly connected to the upper part of the valve stem;

[0024] The retaining member is in a compressed state;

[0025] The valve stem contacts the sealing surface by the restoring force of the retainer and forms the sealing structure.

[0026] Furthermore, the sealing surface is a conical surface;

[0027] The upper portion of the valve stem can extend to the upper end of the conical surface and limit the upward movement of the valve stem through the conical surface.

[0028] The present invention discloses a variable pitch screw vacuum pump, in which the over-compression eliminating device as described above is integrated.

[0029] Furthermore, the over-compression elimination device is integrated into the pump body of the vacuum pump, and the inlet side of the valve body of the over-compression elimination device is connected to the pump chamber on the driven screw side of the pump body, and the outlet side of the valve body of the over-compression elimination device is connected to the outside.

[0030] In the above technical solution, the over-compression elimination device and variable pitch screw vacuum pump provided by the present invention have the following beneficial effects:

[0031] The over-compression eliminating device of the present invention keeps the valve stem and the valve body sealed at all times by means of a retaining member. When the pressure in the pump chamber connected thereto is over-pressured, the pressure of the compressed air offsets the restoring force of the retaining member to drive the valve stem to move so as to achieve communication with the outside world, thereby achieving pressure relief. This structure effectively reduces the exhaust temperature and shaft power consumption of the variable pitch screw vacuum pump, and improves operating efficiency, reliability and air extraction performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0033] Figure 1 A schematic diagram of the structure of an over-compression elimination device provided by an embodiment of the present invention;

[0034] Figure 2 Schematic diagram of the structure of a variable pitch screw vacuum pump with an integrated over-compression elimination device provided in an embodiment of the present invention Figure 1 ;

[0035] Figure 3 Schematic diagram of the structure of a variable pitch screw vacuum pump with an integrated over-compression elimination device provided in an embodiment of the present invention Figure 2 ;

[0036] Figure 4 A comparison diagram of the pumping rate curves of the variable pitch screw vacuum pumps provided in the embodiments of the present invention with and without the over-compression elimination device of the present invention;

[0037] Figure 5 A comparison diagram of power consumption curves of variable pitch screw vacuum pumps provided in an embodiment of the present invention with and without the over-compression eliminating device of the present invention.

[0038] Description of reference numerals:

[0039] 1. Over-compression elimination device; 2. Pump body; 3. Pressure chamber;

[0040] 101, valve body; 102, inlet; 103, outlet; 104, valve stem; 105, valve cover; 106, retainer;

[0041] 10101, sealing surface;

[0042] 10501, valve cover body; 10502, valve cover mounting body; 10503, valve cover hole;

[0043] 201, driven screw side pump chamber;

[0044] 401. Pumping rate curve of a variable pitch screw vacuum pump equipped with an over-compression elimination device;

[0045] 402. The pumping rate curve of the variable pitch screw vacuum pump in the prior art;

[0046] 501. Power consumption curve of a variable pitch screw vacuum pump equipped with an over-compression elimination device;

[0047] 502. Power consumption curve of variable pitch screw vacuum pump in the prior art. DETAILED DESCRIPTION

[0048] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0049] Embodiment 1:

[0050] Embodiment 1 of the present application discloses the structure and working principle of an over-compression elimination device;

[0051] See also Figure 1 As shown;

[0052] The over-compression elimination device 1 of the present invention comprises:

[0053] Valve body 101;

[0054] A valve stem 104 movably connected to the valve body 101;

[0055] The valve body 101 has an inlet 102 and an outlet 103;

[0056] A valve cover 105 is installed on one side of the outlet 103 of the valve body 101, one end of the valve stem 101 is connected to the valve cover 105, and the other end of the valve stem 104 extends along the axial direction of the valve body 101 to the side of the inlet 102 of the valve body 101;

[0057] One end of the inlet 102 of the valve body 101 of the over-compression elimination device 1 is communicated with the pressure chamber 3 of the external mechanism;

[0058] The position where the valve body 101 communicates with the pressure chamber 3 is configured as a sealing surface 10101;

[0059] One end of the valve stem 104 close to the inlet 102 can extend to the sealing surface 10101 to isolate the valve body 101 from the pressure chamber 3 of the external mechanism;

[0060] A retaining member 106 is integrated in the valve body 101 to keep the valve stem 104 placed in the sealing surface 10101 to form a sealing structure.

[0061] Specifically, the elimination device in the first embodiment of the present invention has a valve body 101 and a valve stem 104 movably connected to the valve body 101 as main components, wherein the inlet 102 of the valve body 101 is connected to the chamber that needs to be depressurized, that is, the pressure chamber 3 mentioned above, and the outlet 103 is connected to the outside world. When the pressure in the pressure chamber 3 is too high, the pressure of the compressed air exceeds the holding force of the retaining member 106. At this time, the retaining member will be deformed by the pressure of the compressed air, thereby driving the valve stem 104 to move, releasing the sealing state, and realizing the drainage and release of the compressed air. When the pressure in the pressure chamber 3 is less than the external pressure, under the holding action of the retaining member 106, the valve stem 104 is always in contact with the sealing surface 10101 of the valve body 101 and forms a sealing structure. This result has a wide range of applications and is sensitive to reaction.

[0062] Preferably, in this embodiment, the valve stem 104 is configured in two states, namely:

[0063] In the first state, when the pressure in the pressure chamber 3 of the external mechanism is not greater than the pressure at the outlet of the valve body 101, the valve stem 104 contacts the sealing surface 10101 through the retaining member 106 and forms a sealing structure to isolate the valve body 101 and the pressure chamber 3;

[0064] In the second state, when the pressure in the pressure chamber 3 of the external mechanism is greater than the pressure at the outlet 103 of the valve body 101 , the valve stem 104 moves along the axial direction of the valve body 101 toward the outlet 103 to move away from the sealing surface 10101 .

[0065] The valve stem 104 of the first embodiment has the above two states, and can react relatively sensitively and switch the sealing state according to the pressure in the pressure chamber 3 connected thereto, so as to achieve rapid pressure relief.

[0066] The retainer 106 is a spring. Of course, as long as the retainer 106 can ensure the above functions, the retainer 106 can also be other structural forms, which will not be described here.

[0067] Preferably, in this embodiment, the valve body 101 is a hollow structure;

[0068] The valve cover 105 includes a valve cover body 10501 assembled with the valve body 101, and a valve cover mounting body 10502 formed at the axis of the valve cover body 10501;

[0069] The lower portion of the valve stem 104 is embedded in the valve cover mounting body 10502 to be assembled with the valve cover 105;

[0070] The valve cover body 10501 is provided with valve cover holes 10503 along its circumference.

[0071] One end of the retainer 106 is fixedly connected to the valve cover mounting body 10502, and the other end of the retainer 106 is fixedly connected to the upper part of the valve stem 104;

[0072] The retaining member 106 is in a compressed state;

[0073] The valve stem 104 contacts the sealing surface 10101 through the restoring force of the retainer 106 and forms a sealing structure.

[0074] This embodiment specifically introduces the structure of the valve cover 105 assembled with the valve body 101, wherein, in order to form a connection device with the valve body 101 and ensure that the valve stem 104 can move along the axial direction of the valve body 101, the middle part of the valve cover body 10501 has a valve cover mounting body 10502, and the valve cover mounting body 10502 has a through hole that allows the valve stem 104 to move. The function of the through hole is to guide the movement of the valve stem 104 on the one hand, and on the other hand, the valve stem 104 can always maintain a certain state in a certain state. In addition, the valve cover mounting body 10502 in this embodiment also serves as a mounting structure of the retainer 106, and is connected to the valve stem 104 to maintain the required working state of the valve stem 104.

[0075] As a further preferred technical solution:

[0076] The sealing surface 10101 mentioned above is a conical surface;

[0077] The upper portion of the valve stem 104 can extend to the upper end of the conical surface and the upward movement of the valve stem 104 is limited by the conical surface.

[0078] The sealing surface 10101 is a truncated cone structure as a whole, and its cross-sectional structure is a conical surface extending from top to bottom toward the outside. This design can ensure that when the valve stem 104 moves upward, it gradually extends upward through the conical surface as a guide, and can also form a restriction with the valve stem 104 through the conical surface to constrain the valve stem 104 to continue to move upward, so as to form the above-mentioned sealing structure. Therefore, the upper end of the valve stem 104 in this embodiment also needs to be processed into a structure matching the conical surface structure.

[0079] Embodiment 2:

[0080] See also Figures 2 to 3 As shown, this second embodiment discloses the structure and working principle of a variable pitch screw vacuum pump integrated with an over-compression elimination device 1 .

[0081] The present invention discloses a variable pitch screw vacuum pump, in which the over-compression eliminating device 1 as described above is integrated.

[0082] Preferably, in this embodiment, the over-compression elimination device 1 is integrated into the pump body 2 of the vacuum pump, and the inlet 102 side of the valve body 101 of the over-compression elimination device 1 is connected to the driven screw side pump chamber 01 of the pump body 2, and the outlet 103 side of the valve body 101 of the over-compression elimination device 1 is connected to the outside.

[0083] The pump body 2 at the driven screw side pump chamber 201 of the variable pitch screw vacuum pump in the second embodiment is embedded with the above-mentioned over-compression elimination device 1, which is integrally embedded in the pump body 2 and serves as a communication channel and sealing structure between the driven screw side pump chamber 201 and the outside world. The pressure in the driven screw side pump chamber 201 is also based on the exhaust pressure, that is, the atmospheric pressure (101325Pa). When the pressure in the driven screw side pump chamber 201 is greater than the exhaust pressure, it offsets the restoring force of the spring and drives the valve stem 104 to move along the axis of the valve body 101 to release the pressure in the driven screw side pump chamber 201; on the contrary, the valve stem 104 is always kept in a sealing structure with the valve body 101 under the action of the restoring force of the spring.

[0084] See also Figures 4 to 5 As shown;

[0085] Figure 4 A comparison diagram of the pumping rate curves of the variable pitch screw vacuum pumps with and without the over-compression elimination device 1 of the present invention is shown;

[0086] Figure 4 401 is a pumping rate curve of a variable pitch screw vacuum pump equipped with the over-compression elimination device 1 of the variable pitch screw vacuum pump of the present invention; 402 is a pumping rate curve of a variable pitch screw vacuum pump not equipped with the over-compression elimination device 1 of the variable pitch screw vacuum pump of the present invention.

[0087] The horizontal axis is the inlet pressure of the variable pitch screw vacuum pump, in hPa;

[0088] The vertical axis is the pumping rate, in L / s.

[0089] Figure 5 A comparison diagram of power consumption curves of variable pitch screw vacuum pumps with and without the over-compression elimination device 1 of the present invention is shown.

[0090] Figure 5 501 is a power consumption curve of a variable pitch screw vacuum pump equipped with the over-compression elimination device 1 of the variable pitch screw vacuum pump of the present invention; 502 is a power consumption curve of a variable pitch screw vacuum pump not equipped with the over-compression elimination device 1 of the variable pitch screw vacuum pump of the present invention.

[0091] The horizontal axis is the inlet pressure of the variable pitch screw vacuum pump, in hPa;

[0092] The vertical axis is power consumption, in kW.

[0093] By comparing the performance test data of the variable pitch screw vacuum pump with the over-compression elimination device 1 and the variable pitch screw vacuum pump without the over-compression elimination device 1, it can be seen that when the exhaust pressure of the screw vacuum pump is atmospheric pressure (i.e., 101325Pa), when the inlet pressure is relatively low, the performance data of the variable pitch screw vacuum pump with the over-compression elimination device 1 and the variable pitch screw vacuum pump without the over-compression elimination device 1 are basically the same; when the inlet pressure is higher than 500hPa, the pumping rate of the variable pitch screw vacuum pump with the over-compression elimination device 1 is significantly higher than that of the variable pitch screw vacuum pump without the over-compression elimination device 1, and the shaft power of the variable pitch screw vacuum pump with the over-compression elimination device 1 is significantly lower than that of the variable pitch screw vacuum pump without the over-compression elimination device 1, and the inlet pressure from 500hPa to 1000hPa is part of the working pressure range of each screw vacuum pump, so the setting of the over-compression elimination device 1 of the present invention has a significant effect on energy saving and efficiency improvement of the variable pitch screw vacuum pump.

[0094] In the above technical solution, the over-compression elimination device and variable pitch screw vacuum pump provided by the present invention have the following beneficial effects:

[0095] The over-compression eliminating device 1 of the present invention keeps the valve stem 104 and the valve body 101 sealed at all times through the retaining member 106. When the pressure in the pump chamber connected thereto is over-pressured, the pressure of the compressed air offsets the restoring force of the retaining member 106 to drive the valve stem 104 to move, so as to achieve communication with the outside world, thereby achieving pressure relief. This structure effectively reduces the exhaust temperature and shaft power consumption of the variable pitch screw vacuum pump, and improves the operating efficiency, reliability and exhaust performance.

[0096] The above description is only by way of illustration of certain exemplary embodiments of the present invention. It is undoubted that those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. An over-compression elimination device, characterized in that: The over-compression elimination device (1) comprises: Valve body (101); A valve stem (104) movably connected to the valve body (101); The valve body (101) has an inlet (102) and an outlet (103); A valve cover (105) is installed on one side of the outlet (103) of the valve body (101), one end of the valve stem (104) is connected to the valve cover (105), and the other end of the valve stem (104) extends along the axial direction of the valve body (101) to the inlet (102) side of the valve body (101); One end of the inlet (102) of the valve body (101) of the over-compression elimination device (1) is in communication with a pressure chamber (3) of an external mechanism; The position where the valve body (101) communicates with the pressure chamber (3) is configured as a sealing surface (10101); An end of the valve stem (104) close to the inlet (102) can extend to the sealing surface (10101) to isolate the valve body (101) from the pressure chamber (3) of the external mechanism; The valve body (101) is integrated with a retaining member (106) for retaining the valve stem (104) in the sealing surface (10101) to form a sealing structure; The valve stem (104) is configured in two states: In the first state, when the pressure in the pressure chamber (3) of the external mechanism is not greater than the pressure at the outlet (103) of the valve body (101), the valve stem (104) contacts the sealing surface (10101) through the retaining member (106) and forms a sealing structure to isolate the valve body (101) and the pressure chamber (3); The second state is when the pressure in the pressure chamber (3) of the external mechanism is greater than the pressure at the outlet (103) of the valve body (101), the valve stem (104) moves along the axial direction of the valve body (101) toward the outlet (103) to move away from the sealing surface (10101); The valve body (101) is a hollow structure; The valve cover (105) comprises a valve cover body (10501) assembled with the valve body (101), and a valve cover mounting body (10502) formed at the axis of the valve cover body (10501); The lower portion of the valve stem (104) is embedded in the valve cover mounting body (10502) to be assembled with the valve cover (105); The valve cover body (10501) is provided with valve cover holes (10503) arranged along its circumference; One end of the retaining member (106) is fixedly connected to the valve cover mounting body (10502), and the other end of the retaining member (106) is fixedly connected to the upper part of the valve stem (104); The retaining member (106) is in a compressed state; The valve stem (104) contacts the sealing surface (10101) through the restoring force of the retaining member (106) and forms the sealing structure.

2. The over-compression elimination device according to claim 1, characterized in that: The retaining member (106) is a spring.

3. The over-compression elimination device according to claim 1, characterized in that: The sealing surface (10101) is a conical surface; The upper portion of the valve stem (104) can extend to the upper end of the conical surface and limit the upward movement of the valve stem (104) through the conical surface.

4. Variable pitch screw vacuum pump, characterized in that: The vacuum pump is integrated with an over-compression elimination device (1) as claimed in any one of claims 1 to 3.

5. The variable pitch screw vacuum pump according to claim 4, characterized in that: The over-compression eliminating device (1) is integrated into the pump body (2) of the vacuum pump, and the inlet (102) side of the valve body (101) of the over-compression eliminating device (1) is connected to the driven screw side pump chamber (201) of the pump body (2), and the outlet (103) side of the valve body (101) of the over-compression eliminating device (1) is connected to the outside.

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