Roots vacuum pump

Abstract

The utility model belongs to the technical field of vacuum pump. It solves the problem of poor lubrication and cooling effect of lubricating oil on Roots vacuum pump in prior art. Provide a kind of Roots vacuum pump, including pump shell, first rotation axis and second rotation axis, first rotation axis and second rotation axis are driven by gear engagement between, the end of both first rotation axis and second rotation axis is respectively set on pump shell by bearing, first rotation axis and second rotation axis are respectively equipped with oil flinger, oil flinger and bearing are located in lubricating oil cavity, two lubricating oil cavities are connected by spray pipeline and oil return line and form closed loop circuit, oil pump and oil tank are sequentially connected on spray pipeline, oil tank is communicated with oil return line, filter is provided on oil return line, spray pipeline is inserted into lubricating oil cavity and is provided with several spray heads on the part of insertion, several spray heads are respectively set towards bearing and gear. The utility model has the advantages of being capable of improving the lubrication and cooling effect of lubricating oil on Roots vacuum pump.

Description

Technical Field

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

[0002] A Roots vacuum pump is a type of variable displacement vacuum pump containing two lobe-shaped rotors rotating synchronously in opposite directions. The rotors and the rotors themselves have small gaps that prevent them from contacting each other. For example, Chinese patent literature discloses a lubrication structure for a Roots vacuum pump (application number: 201921365739.7), which includes a shaft and a housing. The shaft is equipped with a bearing and an oil slinger. The bearing has a bearing housing. The housing includes an outer shell and an inner shell, with a lubrication chamber for holding lubricating oil formed between them. The inner shell has a bearing cap, and an oil sump is formed between the bearing cap and the bearing. The inner shell has an oil inlet channel, the bearing housing has an oil passage groove, the annular groove has a sludge collection groove, and a buffer cavity exists between the bearing housing and the bottom of the circular groove.

[0003] The lubrication structure of this Roots vacuum pump has the following shortcomings during use: It relies solely on splash lubrication via an oil slinger, and the amount of oil slingered depends entirely on the rotational speed of the slinger (i.e., the pump shaft speed) and the immersion depth. This results in uncontrollable and unstable oil supply. Furthermore, the distribution of splash lubricating oil droplets is random and uncontrollable. For friction points that are far away, high up, obstructed, or have a special orientation, the oil droplets may not reach them or may not reach them sufficiently, leading to uneven oil film distribution and creating lubrication "blind spots." This results in poor lubrication or even dry friction in these areas. Additionally, the lubrication structure relies mainly on the lubricating oil being thrown up and then falling back to carry away some heat, failing to provide sufficient and directional cooling oil flow. This easily leads to localized overheating, low cooling efficiency, and accelerated component wear. Summary of the Invention

[0004] The purpose of this invention is to address the aforementioned problems in existing technologies by proposing a Roots vacuum pump. The technical problem this invention aims to solve is how to improve the lubrication and cooling effect of lubricating oil on the Roots vacuum pump.

[0005] The objective of this utility model can be achieved through the following technical solutions:

[0006] A Roots vacuum pump includes a pump housing with lubricating oil chambers at both ends, and a first rotating shaft and a second rotating shaft disposed within the pump housing. The first and second rotating shafts are driven by gear meshing. The ends of both the first and second rotating shafts are respectively mounted on the pump housing via bearings. Oil slingers are also fitted onto the outer portions of both the first and second rotating shafts of the bearings. The oil slingers and bearings are located within the lubricating oil chambers. The pump is characterized in that the two lubricating oil chambers are connected to form a closed-loop circuit via a spray pipe and a return oil pipe. An oil pump and an oil tank are sequentially connected to the spray pipe. The oil tank is connected to the return oil pipe, which is equipped with a filter. The spray pipe extends into the lubricating oil chamber and has a plurality of nozzles at its extended portion, with the nozzles facing the bearings and gears respectively.

[0007] This Roots vacuum pump, while retaining the original splash lubrication system, forms a closed-loop lubrication circuit by connecting a spray pipe and a return oil pipe between the two lubrication chambers. The filter on the return oil pipe filters the lubricating oil, ensuring the cleanliness of the recovered lubricating oil. At the same time, by adding an oil pump at the part of the spray pipe that extends into the lubrication chamber, pressurized lubricating oil is sprayed at key lubrication points such as bearings and gears, achieving precise and controllable lubricating oil supply and improving the penetration of the lubricating oil. This ensures that the lubricating oil evenly covers key friction pairs such as gears and bearings, reduces the risk of local dry friction, and provides sufficient and directional cooling oil flow, thereby improving the lubrication and cooling effect of the Roots vacuum pump.

[0008] In the aforementioned Roots vacuum pump, the spray pipe has a first spray section disposed opposite to the outer peripheral side of the gear and a second spray section disposed opposite to the end side of the bearing. The first spray section is arc-shaped and has multiple nozzles facing the outer peripheral surface of the gear, while the second spray section is annular and has multiple nozzles facing the end face of the bearing. This further ensures that the lubricating oil can evenly cover the gear meshing surface and bearing raceway, reducing the risk of local dry friction and providing sufficient and directional cooling oil flow to these parts, thereby further improving the lubrication and cooling effect of the lubricating oil on the Roots vacuum pump.

[0009] In the aforementioned Roots vacuum pump, a PLC controller is mounted on the pump casing, and a temperature sensor and a cooler with a fan are installed on the oil return line. The oil pump, temperature sensor, and cooler are electrically connected to the PLC controller. The PLC controller can control the fan speed and oil pump pressure based on the temperature detected by the temperature sensor. This eliminates dependence on cooling water (especially suitable for water-scarce or high ambient temperature scenarios). The PLC controller automatically adjusts the oil pump pressure and fan speed based on the temperature sensor readings, improving lubrication and cooling efficiency and effectiveness.

[0010] In the aforementioned Roots vacuum pump, a flow regulating valve is also installed on the spray pipeline. This flow regulating valve is electrically connected to a PLC controller, which controls the opening of the flow regulating valve based on the temperature detected by the temperature sensor. The PLC controller adjusts the opening of the flow regulating valve according to the temperature sensor reading, thereby regulating the amount of lubricating oil output by the pump. Specifically, when the temperature sensor reading is higher than a set value, the PLC controller increases the opening of the flow regulating valve, increasing the lubricating oil supply. Conversely, when the temperature sensor reading is lower than the set value, the PLC controller decreases the opening of the flow regulating valve, reducing the lubricating oil supply, thus achieving precise "on-demand lubrication."

[0011] In the aforementioned Roots vacuum pump, the oil return line has a cylindrical coil section located at the exhaust port of the pump casing. Adding this coil section to the exhaust port of the Roots vacuum pump, made of a thermally conductive material such as copper, allows for convection heat exchange with the air, reducing the exhaust gas temperature. This actively cools the gas at the inlet of the next stage pump (by approximately 5-10°C), preventing thermal expansion and efficiency loss caused by high-temperature gases. Furthermore, the coil section can work in conjunction with a cooler to improve the overall thermal stability of the Roots vacuum pump.

[0012] In the aforementioned Roots vacuum pump, there are two temperature sensors and two coolers, each located on opposite sides of the coil section. This two-stage, series-connected arrangement of temperature sensors and coolers allows for better reduction of the lubricating oil temperature. Specifically, when the temperature difference detected by the two sensors exceeds 10°C, the PLC controller increases the fan speed of both coolers to enhance cooling. Conversely, when the temperature difference is less than 5°C, the PLC controller reduces the fan speed of both coolers, thus improving lubricating oil temperature control.

[0013] In the aforementioned Roots vacuum pump, the two ends of the return oil line are respectively connected to the bottom of two lubricating oil chambers and are each equipped with a valve to control their on / off state. The return oil line's connection to the bottom of the lubricating oil chambers allows for gravity-assisted lubricating oil return, while the valves enable users to more easily control the on / off state of the return oil line, facilitating inspection, maintenance, and cleaning operations.

[0014] In the aforementioned Roots vacuum pump, the nozzle of the nozzle facing the bearing is conical, and the nozzle of the nozzle facing the gear is V-shaped. The conical nozzle causes the sprayed lubricating oil to form a three-dimensional cone shape, and the spray area can cover a circular area, allowing the lubricating oil to better cover the bearing raceway. The V-shaped nozzle causes the sprayed lubricating oil to form a two-dimensional fan shape, and the spray area can cover a fan-shaped strip area, allowing the lubricating oil to better cover the gear meshing surface.

[0015] Compared with existing technologies, the advantages of the Ben Roots vacuum pump are as follows: While maintaining the original splash lubrication of the oil slinger, the Ben Roots vacuum pump forms a closed-loop lubrication circuit by connecting a spray pipeline and a return oil pipeline between the two lubrication oil chambers. The filter on the return oil pipeline can filter the lubricating oil to ensure the cleanliness of the recovered lubricating oil. At the same time, by adding an oil pump to the spray pipeline, the lubricating oil is sprayed at key lubrication parts such as bearings and gears under pressure, achieving precise and controllable lubricating oil supply and improving the permeability of the lubricating oil. This ensures that the lubricating oil evenly covers the gear meshing surface and bearing raceway, reduces the risk of local dry friction, and provides sufficient and directional cooling oil flow, thereby improving the lubrication and cooling effect of the lubricating oil on the Roots vacuum pump. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the Ben Roots vacuum pump.

[0017] Figure 2 yes Figure 1 Sectional view at point AA.

[0018] Figure 3 yes Figure 1 Sectional view at point BB.

[0019] In the diagram, 1. Pump housing; 1a. Lubricating oil chamber; 1b. Exhaust port; 2. First rotating shaft; 3. Second rotating shaft; 4. Gear; 5. Bearing; 6. Oil slinger; 7. Spray pipe; 7a. Nozzle; 7b. First spray section; 7c. Second spray section; 8. Return oil pipe; 8a. Coil section; 9. Oil pump; 10. Oil tank; 11. Filter; 12. Temperature sensor; 13. Cooler; 14. Flow regulating valve; 15. Valve. Detailed Implementation

[0020] 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.

[0021] A Roots vacuum pump, reference Figure 1-3The system includes a pump housing 1 with lubricating oil chambers 1a at both ends, and a first rotating shaft 2 and a second rotating shaft 3 disposed within the pump housing 1. The first rotating shaft 2 and the second rotating shaft 3 are driven by gear 4. The ends of the first rotating shaft 2 and the second rotating shaft 3 are respectively mounted on the pump housing 1 via bearings 5. Oil slingers 6 are also fitted on the parts of the first rotating shaft 2 and the second rotating shaft 3 located outside the bearings 5. The oil slingers 6 and the bearings 5 ​​are both located within the lubricating oil chambers 1a. The two lubricating oil chambers 1a are connected to form a closed loop circuit through a spray pipe 7 and a return oil pipe 8. An oil pump 9 and an oil tank 10 are connected sequentially to the spray pipe 7. The oil tank 10 is connected to the return oil pipe 8. A filter 11 is disposed on the return oil pipe 8. The spray pipe 7 extends into the lubricating oil chambers 1a and is provided with a plurality of nozzles 7a at the extended part. The plurality of nozzles 7a are respectively positioned facing the bearings 5 ​​and the gears 4.

[0022] Reference Figure 1 , Figure 2 and Figure 3 Specifically, the spray pipe 7 has a first spray section 7b disposed opposite to the outer peripheral side of the gear 4 and a second spray section 7c disposed opposite to the end side of the bearing 5. The first spray section 7b is arc-shaped and has a plurality of nozzles 7a facing the outer peripheral surface of the gear 4, and the second spray section 7c is annular and has a plurality of nozzles 7a facing the end face of the bearing 5.

[0023] Reference Figure 1 Furthermore, a PLC controller is installed on the pump housing 1, and a temperature sensor 12 and a cooler 13 with a fan are also installed on the oil return pipeline 8. The oil pump 9, temperature sensor 12, and cooler 13 are electrically connected to the PLC controller. The PLC controller can control the speed of the fan of the cooler 13 and the pressure of the oil pump 9 according to the temperature detected by the temperature sensor 12. A flow regulating valve 14 is also installed on the spray pipeline 7. The flow regulating valve 14 is electrically connected to the PLC controller. The PLC controller can control the opening degree of the flow regulating valve 14 according to the temperature detected by the temperature sensor 12. The PLC controller (not shown in the figure), temperature sensor 12, fan-equipped cooler 13, and flow regulating valve 14 can all use existing electronic components, which will not be elaborated here. Generally, the PLC controller only needs to have the function of acquiring the signal from the temperature sensor 12, controlling the speed of the fan in the cooler 13 and the pressure of the oil pump 9, and adjusting the opening of the flow regulating valve 14. For example, an existing S7-200CPU224XP PLC controller can be used. The fins of the cooler 13 are preferably made of aluminum alloy, with a fin spacing ≤2mm. The fan on the cooler is preferably a variable frequency brushless motor with a noise level below 50dB.

[0024] Reference Figure 1 More specifically, the return oil line 8 has a cylindrical coil section 8a, which is located on the exhaust port 1b of the pump housing 1. There are two temperature sensors 12 and two coolers 13, each located on opposite sides of the coil section 8a.

[0025] In this embodiment, the two ends of the return oil pipeline 8 are preferably connected to the bottom of the two lubricating oil chambers 1a, and each is equipped with a valve 15 for controlling the on / off state. The nozzle of the spray head 7a facing the bearing 5 is conical, and the nozzle of the spray head 7a facing the gear 4 is V-shaped.

[0026] This Roots vacuum pump, while retaining the original splash lubrication system of the oil slinger 6, forms a closed-loop lubrication circuit by connecting a spray pipe 7 and a return oil pipe 8 between the two lubrication oil chambers 1a. The filter 11 on the return oil pipe 8 filters the returned lubricating oil, ensuring the cleanliness of the recovered lubricating oil. Simultaneously, by adding an oil pump 9 to the spray pipe 7, pressurized lubricating oil is sprayed onto key lubrication points such as the bearing 5 and gear 4, achieving precise and controllable lubrication supply and improving the penetration of the lubricating oil. This ensures that the lubricating oil evenly covers the meshing surface of the gear 4 and the raceway of the bearing 5, reducing the risk of localized dry friction and providing sufficient and directional cooling oil flow, thereby improving the lubrication and cooling effect of the lubricating oil on the Roots vacuum pump. Furthermore, the spray pipe 7, return oil pipe 8, oil pump 9, fan-equipped cooler 13, and filter 11 of this Roots vacuum pump are all located outside the pump casing 1, facilitating maintenance and upgrades.

[0027] 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 substitute them, without departing from the spirit of this utility model or exceeding the scope defined by the appended claims.

Claims

1. A Roots vacuum pump, comprising a pump housing (1) having lubricating oil chambers (1a) at both ends, and a first rotating shaft (2) and a second rotating shaft (3) disposed within the pump housing (1), wherein the first rotating shaft (2) and the second rotating shaft (3) are driven by gear meshing (4), and the ends of both the first rotating shaft (2) and the second rotating shaft (3) are respectively disposed on the pump housing (1) via bearings (5), and oil slingers (6) are respectively fitted onto the portions of the first rotating shaft (2) and the second rotating shaft (3) located outside the bearings (5), wherein the oil slingers (6) and the bearings (5) are both located within the lubricating oil chambers (1a), characterized in that, Two lubricating oil chambers (1a) are connected to form a closed loop through a spray pipe (7) and a return oil pipe (8). An oil pump (9) and an oil tank (10) are connected in sequence to the spray pipe (7). The oil tank (10) is connected to the return oil pipe (8). A filter (11) is installed on the return oil pipe (8). The spray pipe (7) extends into the lubricating oil chamber (1a) and is provided with several nozzles (7a) at the part where it extends. The nozzles (7a) are respectively positioned facing the bearing (5) and the gear (4).

2. A Roots vacuum pump according to claim 1, characterized in that, The spray pipe (7) has a first spray section (7b) disposed opposite to the outer peripheral side of the gear (4) and a second spray section (7c) disposed opposite to the end side of the bearing (5). The first spray section (7b) is arc-shaped and has a plurality of nozzles (7a) facing the outer peripheral surface of the gear (4). The second spray section (7c) is annular and has a plurality of nozzles (7a) facing the end face of the bearing (5).

3. A Roots vacuum pump according to claim 1 or 2, characterized in that, A PLC controller is installed on the pump housing (1), and a temperature sensor (12) and a cooler (13) with a fan are also installed on the oil return pipeline (8). The oil pump (9), temperature sensor (12) and cooler (13) are electrically connected to the PLC controller. The PLC controller can control the speed of the fan of the cooler (13) and the pressure of the oil pump (9) according to the temperature detected by the temperature sensor (12).

4. A Roots vacuum pump according to claim 3, characterized in that, The spray pipe (7) is also equipped with a flow regulating valve (14), which is electrically connected to the PLC controller. The PLC controller can control the opening degree of the flow regulating valve (14) according to the temperature detected by the temperature sensor (12).

5. A Roots vacuum pump according to claim 3, characterized in that, The return oil line (8) has a cylindrical coil section (8a) located on the exhaust port (1b) of the pump housing (1).

6. A Roots vacuum pump according to claim 5, characterized in that, There are two temperature sensors (12) and two coolers (13), and the two temperature sensors (12) and the two coolers (13) are respectively arranged on both sides of the coil section (8a).

7. A Roots vacuum pump according to claim 3, characterized in that, The two ends of the return oil pipeline (8) are respectively connected to the bottom of the two lubricating oil chambers (1a) and are each equipped with a valve (15) to control the on / off state.

8. A Roots vacuum pump according to claim 1 or 2, characterized in that, The nozzle of the nozzle (7a) facing the bearing (5) is conical, and the nozzle of the nozzle (7a) facing the gear (4) is V-shaped.

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