Roots pump

Abstract

The utility model provides a roots pump and belongs to the technical field of pumps. The problem that the pressure in a lubricating oil cavity and the pressure in a vacuum cavity are unbalanced before a roots pump is started in the prior art is solved. The roots pump comprises a pump body, a first lubricating oil cavity, a vacuum cavity and a second lubricating oil cavity which are not communicated with one another are sequentially and adjacently arranged in the pump body, a communicating pipe with three communicating openings is arranged on the pump body, and a first communicating opening and a second communicating opening which are located in the two ends of the communicating pipe are communicated with the vacuum cavity and the second lubricating oil cavity of the pump body respectively. A third communicating port located in the side wall of the communicating pipe communicates with the first lubricating oil cavity, the second communicating port is provided with a first one-way valve used for enabling airflow in the second lubricating oil cavity to be in one-way communication with the communicating pipe, and the third communicating port is provided with a second one-way valve used for enabling airflow in the first lubricating oil cavity to be in one-way communication with the communicating pipe. The utility model has the advantage that the pressure balance in the lubricating oil cavity and the vacuum cavity of the roots pump can be quickly realized.

Description

Technical Field

[0001] This utility model belongs to the field of pump technology and relates to a Roots pump. Background Technology

[0002] A Roots pump is a type of variable displacement vacuum pump containing two synchronously rotating, oppositely oriented lobe rotors. The rotors and the inner wall of the pump casing have small gaps that prevent them from contacting each other. When a Roots pump is first started, the pumped medium enters the vacuum chamber through the pump body's inlet and is then pumped away through the casing's exhaust port. Because the bearings on both sides of the Roots pump body are lubricated with splash oil mist, when the pressure in the vacuum chamber fluctuates, the lubricating medium on both sides of the pump body's piston rings will interpenetrate. This not only reduces the quality and purity of the vacuum product in the vacuum chamber but also causes the lubricating oil to emulsify and lose its lubricating function when the pumped medium seeps into the lubricating oil chamber.

[0003] To address the aforementioned issues, Chinese patent literature discloses an air-cooled direct-flow roots pump (application number: 201822274502.X), comprising a housing, within which two meshing rotors are housed. The pump also includes rotor shafts corresponding to the rotors, with each rotor mounted on its respective shaft. The housing has positioning grooves. The pump has two side covers that can be fitted onto the rotor shafts, located at both ends of the rotors. The side covers have protrusions forming positioning rings that can be embedded in the positioning grooves. The pump also has two end covers that are fitted onto the rotor shafts, located at the ends furthest from the side covers. The end covers are bolted to the side covers. A sealing sleeve is fitted onto the rotor shaft between the side covers and the rotor shaft. A shaft sleeve and a bearing are fitted onto the rotor shaft. The pump has a dry sealing ring between the shaft sleeve and the bearing housing.

[0004] The air-cooled straight-flow Roots pump has the following shortcomings during use: Based on the piston ring sealing structure, the air-cooled straight-flow Roots pump adds a sealing ring that effectively isolates the lubricating oil chamber from the vacuum chamber. Under the action of the backing vacuum pump, the vacuum chamber is in a vacuum state before the Roots pump starts, causing an imbalance in pressure between the lubricating oil chamber and the vacuum chamber. This results in both sides of the sealing ring being subjected to alternating pressure impacts for a long time, making the surface of the sealing ring prone to cracking, breakage, fissures, or deformation, leading to failure. Summary of the Invention

[0005] The purpose of this invention is to address the aforementioned problems in existing technologies by proposing a Roots pump. The technical problem this invention aims to solve is how to quickly achieve pressure balance between the lubricating oil chamber and the vacuum chamber of the Roots pump.

[0006] The objective of this utility model can be achieved through the following technical solutions:

[0007] A Roots pump includes a pump body, within which a first non-communicating lubricating oil chamber, a vacuum chamber, and a second lubricating oil chamber are sequentially arranged adjacent to each other. The pump body is characterized by a connecting pipe with three connecting ports. The first and second connecting ports at both ends of the connecting pipe connect to the vacuum chamber and the second lubricating oil chamber of the pump body, respectively. A third connecting port on the side wall of the connecting pipe connects to the first lubricating oil chamber. The second connecting port is equipped with a first one-way valve for unidirectional flow of airflow from the second lubricating oil chamber to the connecting pipe, and the third connecting port is equipped with a second one-way valve for unidirectional flow of airflow from the first lubricating oil chamber to the connecting pipe.

[0008] Under the action of the backing vacuum pump, the vacuum chamber of the Roots pump is in a vacuum state before startup. Under the action of negative pressure, the airflow in the first lubricating oil chamber and the airflow in the second lubricating oil chamber flow rapidly into the vacuum chamber through the connecting pipe, so that the first lubricating oil chamber and the second lubricating oil chamber are pre-evacuated. At the same time, the first one-way valve and the second one-way valve can prevent the backflow of gas, so that the pressure balance between the first lubricating oil chamber, the second lubricating oil chamber and the vacuum chamber can be quickly achieved, and the dynamic balance of the pressure in the three chambers can be realized. On the one hand, it can prevent the lubricating oil in the lubricating oil chamber and the pumped medium in the vacuum chamber from interpenetrating, keeping the pump chamber dry, the pumped medium clean and the lubricating oil clean. On the other hand, it can reduce the shaft seal clamping force, prevent the sealing ring between the lubricating oil chamber and the vacuum chamber from being subjected to pressure impact on both sides for a long time, reduce shaft seal wear, and improve the service life of the sealing ring in the pump body. At the same time, it can also reduce the pressure heating of the lubricating chamber before the Roots pump starts, thereby improving the service life of the Roots pump.

[0009] In addition, the connecting pipe is located outside the pump body, which facilitates the installation, maintenance and replacement of the connecting pipe. During use, the operator can directly observe the working status of the connecting pipe and carry out inspection and maintenance at any time.

[0010] In one type of Roots pump described above, a solenoid valve for controlling its opening and closing is installed on the connecting pipe. The solenoid valve is located between the second check valve and the first connecting port. The connecting pipe of this Roots pump only functions before the Roots pump starts (under the action of the backing vacuum pump, the vacuum chamber of the Roots pump is in a vacuum state before startup). By setting the solenoid valve, the connecting pipe can be cut off, preventing the first lubricating oil chamber, the second lubricating oil chamber, and the vacuum chamber from remaining in a constantly open state. After prolonged use, the pump body temperature may rise, causing the lubricating oil in the first and second lubricating oil chambers to vaporize upon heating, forming oil mist that mixes with the airflow and flows into the vacuum chamber, thus keeping the pumped medium in the vacuum chamber clean.

[0011] In one of the aforementioned Roots pumps, the pump body is further provided with a first venting valve connecting the first lubricating oil chamber and the outside of the pump body. When the Roots pump is shut down, the operator can first open the first venting valve and then stop the Roots pump. This allows the gas in the first lubricating oil chamber to be released, enabling the pressure balance between the first lubricating oil chamber, the second lubricating oil chamber, and the vacuum chamber to be restored.

[0012] In one of the aforementioned Roots pumps, a second venting valve is also provided on the pump body, connecting the second lubricating oil chamber and the outside of the pump body. When the Roots pump is shut down, the operator can first open the second venting valve and then stop the Roots pump. This allows the gas in the second lubricating oil chamber to be released, enabling the pressure balance between the first lubricating oil chamber, the second lubricating oil chamber, and the vacuum chamber to be restored.

[0013] In the aforementioned Roots pump, both the first and second venting valves are electrically operated. Electrically operated valves are easy to install, durable, and highly reliable. Furthermore, they are electrically driven, enabling rapid opening and closing, thereby improving production efficiency and safety, and allowing for high-precision control.

[0014] Compared with existing technologies, the advantages of this Roots pump are as follows: By adding connecting pipes that unidirectionally connect the first lubricating oil chamber and the vacuum chamber, as well as the second lubricating oil chamber and the vacuum chamber, the pressure balance between the first lubricating oil chamber and the second lubricating oil chamber and the vacuum chamber can be quickly achieved before the Roots pump is started. On the one hand, this can prevent the lubricating oil in the lubricating oil chamber and the pumped medium in the vacuum chamber from interpenetrating, keeping the pump chamber dry and the lubricating oil clean. On the other hand, it can reduce the shaft seal clamping force, prevent the sealing rings between the lubricating oil chamber and the vacuum chamber from being subjected to alternating pressure impacts on both sides for a long time, reduce shaft seal wear, and improve the service life of the sealing rings in the pump body, thereby improving the service life of the Roots pump. Attached Figure Description

[0015] Figure 1 This is a cross-sectional structural schematic diagram of the Ben Roots pump.

[0016] In the diagram, 1 is the pump body; 1a is the air inlet; 1b is the exhaust port; 1c is the first lubricating oil chamber; 1d is the vacuum chamber; 1e is the second lubricating oil chamber; 2 is the connecting pipe; 2a is the first connecting port; 2b is the second connecting port; 2c is the third connecting port; 3 is the first check valve; 4 is the second check valve; 5 is the solenoid valve; 6 is the first venting valve; and 7 is the second venting valve. Detailed Implementation

[0017] The following are specific embodiments of the present invention, which are described in conjunction with the accompanying drawings. However, the present invention is not limited to these embodiments.

[0018] A Roots pump, reference Figure 1 The pump body 1 includes an air inlet 1a and an exhaust outlet 1b. Inside the pump body 1, a first non-communicating lubricating oil chamber 1c, a vacuum chamber 1d, and a second lubricating oil chamber 1e are sequentially arranged adjacent to each other. A connecting pipe 2 with three connecting ports is provided on the pump body 1. The first connecting port 2a and the second connecting port 2b at both ends of the connecting pipe 2 connect to the vacuum chamber 1d and the second lubricating oil chamber 1e of the pump body 1, respectively. A third connecting port 2c located on the side wall of the connecting pipe 2 connects to the first lubricating oil chamber 1c. A first one-way valve 3 is provided on the second connecting port 2b to allow airflow in the second lubricating oil chamber 1e to flow unidirectionally towards the connecting pipe 2. A second one-way valve 4 is provided on the third connecting port 2c to allow airflow in the first lubricating oil chamber 1c to flow unidirectionally towards the connecting pipe 2. In this embodiment, preferably, the first connecting port 2a of the connecting pipe 2 is connected to the wall of the exhaust outlet 1b of the pump body 1.

[0019] Under the action of the back vacuum pump, the vacuum chamber of the Roots pump is in a vacuum state before it starts. Under the action of negative pressure, the airflow in the first lubricating oil chamber 1c and the airflow in the second lubricating oil chamber 1e flow rapidly into the vacuum chamber through the connecting pipe 2, so that the first lubricating oil chamber 1c and the second lubricating oil chamber 1e are pre-evacuated. At the same time, the first one-way valve 3 and the second one-way valve 4 can prevent the backflow of gas, so that the pressure balance between the first lubricating oil chamber 1c, the second lubricating oil chamber 1e and the vacuum chamber 1d is quickly achieved, and the dynamic balance of the pressure in the three chambers is realized.

[0020] Furthermore, a solenoid valve 5 for controlling its opening and closing is provided on the connecting pipe 2, and the solenoid valve 5 is located between the second one-way valve 4 and the first connecting port 2a; a first venting valve 6 connecting the first lubricating oil chamber 1c and the outside of the pump body 1 is also provided on the pump body 1; a second venting valve 7 connecting the second lubricating oil chamber 1e and the outside of the pump body 1 is also provided on the pump body 1. In this embodiment, preferably, both the first venting valve 6 and the second venting valve 7 are electric valves.

[0021] The specific embodiments described herein are merely illustrative examples illustrating the spirit of this utility model. Those skilled in the art to which this utility model pertains may make various modifications or additions to the described specific embodiments or use similar methods to replace them, without departing from the spirit of this utility model or exceeding the scope defined by the appended claims.

Claims

1. A Roots pump, comprising a pump body (1), wherein a first lubricating oil chamber (1c), a vacuum chamber (1d), and a second lubricating oil chamber (1e) are sequentially and adjacently arranged without communication with each other, characterized in that, The pump body (1) is provided with a connecting pipe (2) having three connecting ports. The first connecting port (2a) and the second connecting port (2b) located at both ends of the connecting pipe (2) are respectively connected to the vacuum chamber (1d) and the second lubricating oil chamber (1e) of the pump body (1). The third connecting port (2c) located on the side wall of the connecting pipe (2) is connected to the first lubricating oil chamber (1c). The second connecting port (2b) is provided with a first one-way valve (3) for unidirectional flow of air in the second lubricating oil chamber (1e) to the connecting pipe (2). The third connecting port (2c) is provided with a second one-way valve (4) for unidirectional flow of air in the first lubricating oil chamber (1c) to the connecting pipe (2).

2. A Roots pump according to claim 1, characterized in that, The connecting pipe (2) is provided with a solenoid valve (5) for controlling its opening and closing, and the solenoid valve (5) is located between the second one-way valve (4) and the first connecting port (2a).

3. A Roots pump according to claim 1 or 2, characterized in that, The pump body (1) is also provided with a first venting valve (6) that connects the first lubricating oil chamber (1c) and the outside of the pump body (1).

4. A Roots pump according to claim 3, characterized in that, The pump body (1) is also provided with a second venting valve (7) that connects the second lubricating oil chamber (1e) and the outside of the pump body (1).

5. A Roots pump according to claim 4, characterized in that, Both the first venting valve (6) and the second venting valve (7) are electric valves.

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