Vacuum equipment

Abstract

A vacuum apparatus includes at least two vacuum pumps each having at least one lubricant chamber provided for lubricant for lubricating at least one component of the respective vacuum pump. The vacuum device further comprises a central inlet for lubricant and a central outlet for lubricant, the central inlet being connected to the lubricant chamber of each vacuum pump and the central outlet being also connected to the lubricant chamber of each vacuum pump.

Description

TECHNICAL FIELD

[0001] The invention relates to a vacuum device having at least two vacuum pumps. BACKGROUND

[0002] In the vacuum range up to about 10 -4 millibar, two vacuum pumps, for example Roots pumps or screw pumps, can be connected to each other in series in order to increase the total pumping capacity of such a pump unit. The first vacuum pump can be said to act as a "booster" for the following vacuum pump. As a result, the total pumping capacity can be increased by a factor of several compared to the pumping capacity of the following pump.

[0003] Such a pump system having two pumps usually comprises a common housing in which the two vacuum pumps are installed, forming a compact unit. However, vacuum pumps for the vacuum range up to about 10 -4 millibar usually require a working medium or lubricant, for example for lubricating bearings of the pump shafts on which the pump working elements of the vacuum pumps are mounted. During operation of the pump unit, the working medium or lubricant has to be replaced regularly in order to avoid damage to the vacuum pumps.

[0004] If the pumps are enclosed by a common housing as a compact unit, the respective inlets and outlets for the working medium or lubricant on the vacuum pumps are usually not accessible from outside the housing. In order to perform the replacement of the working medium or lubricant, the housing of such a pump system has to be removed and, in some cases, the pump unit has to be partially disassembled. This leads to an increased effort. In the known pump systems, even if the inlets and outlets for the working medium or lubricant on the vacuum pumps are accessible from the outside, the replacement of the working medium or lubricant has to be performed separately for each vacuum pump of the system. SUMMARY

[0005] It is the task of the present invention to provide a vacuum device having at least two vacuum pumps, which allows for a simple replacement of the lubricant of components of the vacuum pumps.

[0006] The task is solved by a vacuum device. The details of the invention are specified in the claims, the description and the drawings.

[0007] The vacuum device comprises at least two vacuum pumps, each having at least one lubricant chamber for storing a lubricant for lubricating at least one component of the respective vacuum pump. In addition, the vacuum device comprises a central inlet for lubricant, which is connected to the lubricant chambers of the vacuum pumps, and a central outlet for lubricant, which is likewise connected to the lubricant chambers of the vacuum pumps.

[0008] The at least two vacuum pumps thus have one or more components which need to be lubricated by means of a lubricant. The vacuum pumps can comprise, for example, a Roots pump or a screw pump or any combination thereof. In such pumps, the shafts carrying the pump working elements can be mounted, for example, on rolling bearings. Such shafts and the corresponding bearings can thus be the components of the vacuum pumps which need to be lubricated. The lubricant can be, for example, oil.

[0009] The central inlet and the central outlet can establish a respective fluid connection with all the lubricant chambers of the at least two vacuum pumps. Since the vacuum device has a central inlet and a central outlet for the lubricant, the lubricant can be fed into and discharged from the lubricant chambers of the individual vacuum pumps in a simple manner, even if the respective inlet and outlet openings of these lubricant chambers cannot be reached from the outside, i.e. from the area outside the vacuum device.

[0010] The vacuum device thus allows a simple replacement of the lubricant without having to remove or disassemble, for example, a housing or other components of the vacuum device. Regular replacement of the lubricant can thus be easily performed at respective predetermined intervals. This can prolong the service life of the vacuum device, since the workload is small and the user does not unnecessarily postpone the replacement of the lubricant, which is often the case in practice with known systems.

[0011] According to one embodiment, the vacuum device comprises a housing which encloses the at least two vacuum pumps. The lubricant chambers of the at least two vacuum pumps can each have a lubricant inlet and outlet which are arranged within the housing.

[0012] Since the housing is present, the respective inlet and outlet of the lubricants cannot usually be reached from the outside, which would make the replacement of the lubricant difficult, as described above. However, the respective inlet and outlet of the lubricant chambers can establish a fluid connection with the central inlet or the central outlet of the vacuum device. Thus, even if the respective inlet and outlet of the lubricant chambers are hidden inside the housing, the lubricant chambers can be reliably filled via the central inlet and the lubricant can be reliably discharged via the central outlet. Since the at least two vacuum pumps are arranged within a common housing and are enclosed by the housing, the vacuum device can overall be designed as a compact unit which requires only a small amount of structural space.

[0013] According to another embodiment, the vacuum device further comprises a control device which is designed to regulate the proportion of lubricant which is fed to the respective lubricant chambers via the central inlet. The control device can thus be provided for distributing the lubricant when filling the respective lubricant chambers. The control device can thus regulate the respective amount of lubricant which can be fed to the individual lubricant chambers when filling them with lubricant. In other words, the control device can enable a prescribed distribution of the lubricant between the individual lubricant chambers, so that they can receive a respective predetermined amount of lubricant. Conversely, an overfilling or underfilling of the individual lubricant chambers can be prevented by means of the control device.

[0014] To this end, the vacuum device can comprise valves which are connected to the control device, for example by means of signal technology, wherein at least one valve each corresponds to one of the lubricant chambers of the vacuum pumps. These valves can be arranged between the central filling neck or the central inlet and the individual lubricant chambers, in order to be able to control the filling of the lubricant chambers with lubricant in a defined manner by means of the control device.

[0015] The control device can also be designed to switch between the valves of the individual lubricant chambers, so that they are filled in succession. By means of this sequential filling, the individual lubricant chambers can be supplied with the required amount of lubricant in a direct and controllable manner.

[0016] The lubricant chambers can also each have a control mechanism for monitoring the lubricant level in the individual lubricant chambers. The individual lubricant level control mechanisms can be functionally and / or signal-technically connected to the control device which is responsible for controlling the filling of the lubricant chambers, so that the control device receives signals from the individual control mechanisms which indicate the respective level of the lubricant chamber to which the control mechanism corresponds.

[0017] By means of the respective control mechanism of the lubricant level of the individual lubricant chambers, it is possible to prevent the lubricant chambers from being filled too much or too little. It is thus possible to ensure by means of the control mechanisms that the lubricant in the individual lubricant chambers reaches the desired level. This can be achieved, for example, in such a way that the control device adjusts the respective valve between the central inlet and the individual lubricant chambers in accordance with the signals of the control mechanisms of the lubricant level, so that the desired level is neither exceeded nor undershot.

[0018] The control mechanisms of the lubricant level of the individual lubricant chambers can comprise float switches which can have, for example, reed contacts. In this way, the control mechanisms of the lubricant level can be implemented in a cost-effective manner. When the filling of the individual lubricant chambers reaches the correct level, the signal of the control mechanism, i.e. the signal of the float switch or the reed contact, can cause the control device to close the respective valve of the corresponding lubricant chamber, thereby stopping the further filling of the lubricant chamber.

[0019] According to a further embodiment, the vacuum pumps each have one rotary shaft. The pump operating elements can be arranged on the respective rotary shafts, which are arranged in the pumping chamber of the respective vacuum pump. Each rotary shaft can be provided with at least two bearings, which can each be connected to one of the lubricant chambers.

[0020] The vacuum device thus has at least four lubricant chambers in this embodiment, wherein two lubricant chambers each correspond to one of the vacuum pumps for supplying lubricant to at least two bearings of the respective shaft of the vacuum pump. The at least four lubricant chambers can each have an independent lubricant inlet and outlet, so that a total of at least four lubricant chamber inlets and four outlets are each connected to the central inlet and the central outlet. If the lubricant replacement is carried out by means of the central inlet and the central outlet in the case of at least four lubricant chambers of the vacuum device, the amount of work for the replacement can be significantly reduced.

[0021] The suction chambers of at least two of the vacuum pumps can be connected to each other. The vacuum pumps can thus be connected in series, so that one pump performs a booster function for the subsequent pump.

[0022] The vacuum pumps can for example comprise a Roots pump and a screw pump, and the Roots pump can be arranged upstream of the screw pump. In this example, the Roots pump can act as a booster pump for the screw pump. The pumping capacity of the pump system consisting of the Roots pump and the screw pump can thus be generally increased by a factor of about 10, compared to the use of the screw pump alone. The pumping capacity represents the volumetric flow rate of the pump per time unit, and is thus for example expressed in liters per second.

[0023] In addition, one of the vacuum pumps can be designed to discharge into the atmosphere. In the case of a series connection of a plurality of vacuum pumps, this can be the last vacuum pump. In this embodiment, the vacuum device thus no longer requires further booster pumps, but can act as an efficient and compact booster pump for other pumps and pump systems, for example for one or more turbomolecular pumps.

[0024] The at least two vacuum pumps can be stacked in the vertical direction. In this embodiment, the vacuum device can have a particularly compact form. Furthermore, if the central inlet is for example arranged on the top side of a common housing of the at least two vacuum pumps or of the vacuum device, and the central outlet is for example arranged on the bottom side, gravity can be utilized when changing the lubricant of the at least two vacuum pumps.

[0025] In addition, a check valve can be arranged between the lubricant chamber of at least one of the vacuum pumps and the central outlet. By means of such a check valve, backflow of lubricant into the lubricant chamber corresponding to the check valve when the lubricant is being discharged can be prevented. Such a backflow can occur for example when the lubricant is being discharged from a vacuum pump or from its lubricant chamber which is arranged vertically above, and flows to the central outlet which can be arranged vertically below the vacuum pump. If there is no check valve, the lubricant can only partially reach the central outlet, but can also flow into the lubricant chamber which is arranged vertically below. The check valve can thus ensure that the lubricant only flows to the central outlet when being discharged, and cannot enter the other lubricant chambers.

[0026] In the case of a stacking of the at least two vacuum pumps in the vertical direction, each check valve can correspond to the lubricant chamber of one or more vacuum pumps which are arranged vertically below at least one of the other vacuum pumps. Each check valve can thus be installed only on the vacuum pump which is arranged vertically lowest, or on all vacuum pumps which are arranged vertically below the highest vacuum pump. Each check valve can thus be arranged upstream of the point at which the lubricant flows together at or in front of the common central outlet, i.e. between the respective outlet of the lubricant chamber and the central outlet. BRIEF DESCRIPTION OF DRAWINGS

[0027] The application will be described below, for example, with reference to the accompanying drawings, in connection with advantageous embodiments. The drawings show schematically: Figure 1 a side view of a vacuum apparatus with two vacuum pumps, Figure 2 a detail view of Figure 1 a lubricant chamber of one of the vacuum pumps. DETAILED DESCRIPTION

[0028] Figure 1 A vacuum apparatus 100 is shown schematically, which comprises a first vacuum pump 110 and a second vacuum pump 120. Both vacuum pumps 110, 120 are arranged within a common housing 130, such that the housing 130 completely encloses the first vacuum pump 110 and the second vacuum pump 120. The first vacuum pump 110 is, for example, a Roots pump, while the second vacuum pump 120 is, for example, a screw pump.

[0029] The first vacuum pump 110 has a first lubricant chamber 112 and a second lubricant chamber 114, which are arranged on opposite sides of a suction chamber 116 of the vacuum pump 110. Similarly, the second vacuum pump 120 has a first lubricant chamber 122 and a second lubricant chamber 124, which are likewise arranged on opposite sides of a suction chamber 126 of the second vacuum pump 120.

[0030] Each lubricant chamber 112, 114, 122, 124 is filled with a lubricant 140, which is provided for lubricating bearings of a respective shaft (both not shown) of the vacuum pumps 110, 120. The respective shaft of the vacuum pumps 110, 120 is driven by a not shown motor of the vacuum pumps 110, 120, respectively, when the vacuum pumps 110, 120 are in operation. A pump working element (not shown) of each vacuum pump 110, 120 is arranged within the respective suction chamber 116, 126 and is connected with the respective shaft, so as to be rotationally driven during operation of the vacuum pumps 110, 120.

[0031] As can be seen in Figure 1 the vacuum pumps 110, 120 are arranged on top of each other in vertical direction, such that the first vacuum pump 110 is located above the second vacuum pump 120 in vertical direction. In addition, the suction chambers 116, 126 of the two vacuum pumps 110, 120 are connected with each other, such that the two vacuum pumps 110, 120 are vacuum-technically in series. As a result, the first vacuum pump 110 acts as a booster for the second vacuum pump 120. Thereby, the pumping capacity of the pump group or the entire vacuum apparatus 100 with the two vacuum pumps 110, 120 can be significantly increased, for example by a factor of 10, compared to the use of the second vacuum pump 120 alone. The pumping capacity refers to the volumetric flow per time of the vacuum pumps 110, 120, for example in liters per second.

[0032] Since the two vacuum pumps 110, 120 are enclosed by the common housing 130 within the vacuum device 100, the connected vacuum pumps 110, 120 form a compact unit, in which the not shown pump inlet of the first vacuum pump 110 can be connected to a vacuum chamber, while the pump outlet of the second vacuum pump 120 can be discharged to the atmosphere. Thereby, an overall booster pump is formed, which is capable of generating a vacuum in the vacuum chamber in the range of up to about 10 -4 millibar, when the first vacuum pump 110 is designed as a Roots pump and the second vacuum pump 120 is designed as a screw pump.

[0033] However, during operation of the vacuum device 100, the two vacuum pumps 110, 120 need to be refilled with lubricant 140 at predetermined intervals, in order to ensure sufficient lubrication of the respective bearings of the vacuum pumps 110, 120, thereby avoiding damage of the respective shafts of the vacuum pumps 110, 120. In particular, the lubricant 140 within the lubricant chambers 112, 114, 122, 124 should be replaced at regular intervals. However, due to the common housing 130, the respective inlets and outlets of the lubricant chambers 112, 114, 122, 124 cannot be reached.

[0034] This means that, in known pump systems with two vacuum pumps and a common housing, the housing has to be at least partially removed or dismantled in order to reach the respective inlets and outlets of the lubricant chambers and to replace the lubricant. Since this involves a high effort, the replacement of the lubricant is often postponed during operation of such compact pump groups with two vacuum pumps and a common housing, until one of the two vacuum pumps fails. In addition, the replacement of the lubricant of each individual vacuum pump also involves a high effort.

[0035] In order to avoid these difficulties, the vacuum device 100 according to the present application has a central inlet 150 for the lubricant 140 and a central outlet 160 for the lubricant 140. The central inlet or filler neck 150 is in fluid communication with the lubricant chambers 112, 114, 122, 124 of the first vacuum pump 110 and of the second vacuum pump 120, respectively, by means of a pipe system 152. Similarly, the lubricant chambers 112, 114, 122, 124 are in fluid communication with the central outlet by means of another pipe system 162. The pipe system 152 between the central inlet 150 and the respective lubricant chambers 112, 114, 122, 124 is indicated in Figure 1 Fig. 1 by solid lines, while the pipe system 162 between the lubricant chambers 112, 114, 122, 124 and the central outlet 160 is indicated by dotted lines.

[0036] The vacuum device 100 further comprises a control device 170 which is provided for controlling the process of the lubricant 140 entering and leaving the lubricant chambers 112, 114, 122, 124 in a controlled manner. This includes the control device 170 dispensing the lubricant 140 to the lubricant chambers 112, 114, 122, 124. For this purpose, the control device 170 is connected with valves 172, 174 which are arranged in the line system 152 or 162, respectively. Each of the lubricant chambers 112, 114, 122, 124 is provided with one inlet valve 172 and one outlet valve 174, respectively.

[0037] The inlet valves 172 are located between the central inlet 150 and the respective inlet of one of the lubricant chambers 112, 114, 122, 124, while the outlet valves 174 are located between the respective one of the lubricant chambers 112, 114, 122, 124 and the central outlet 160. By means of the inlet valves 172, the control device 170 regulates the respective proportion of the lubricant 140 which enters the vacuum device 100 via the central inlet 150 and subsequently flows into the lubricant chambers 112, 114, 122, 124. When filling the lubricant chambers 112, 114, 122, 124, the control device 170 switches between the valves 172, i.e. so that only one inlet valve 172 is open at a certain time. The inlet valves 172 are therefore opened in a sequential order for a predetermined time, so that only one of them is open at a time and all other inlet valves 172 are closed during this time. In this way, the lubricant chambers 112, 114, 122, 124 are filled in a sequential order.

[0038] For controlling the valves 172, 174, there are provided corresponding electrical connection means or wires 176. For the sake of brevity, Figure 1 Only the wire 176 of the lubricant chamber 114 of the vacuum pump 110 is shown in Fig. 1. However, it is to be understood that all inlet valves 172 and all outlet valves 174 are connected with the control device 170 by means of the wires 176.

[0039] Furthermore, there is provided a control means 180 in each of the lubricant chambers 112, 114, 122, 124 for monitoring the level of the lubricant 140 in the respective lubricant chamber 112, 114, 122, 124. The control means 180 of the respective lubricant level is connected with the control device 170 by means of the wire 176. Figure 2The control device 170 is connected to the control mechanisms 180 via lines 176. The control mechanisms 180 are designed to detect the level of the lubricant 140 in the lubricant chambers 112, 114, 122, 124. The control mechanisms 180 are designed to be float switches. The control mechanisms 180 are connected to the control device 170 via lines 176. The control device 170 receives signals from the control mechanisms 180, which signals correspond to the level of the lubricant 140 in the lubricant chambers 112, 114, 122, 124. The signals can indicate, for example, whether a predetermined level of the lubricant 140 in the lubricant chambers 112, 114, 122, 124 has been reached. Depending on the signals, the control device 170 can control the filling of the lubricant chambers 112, 114, 122, 124 via the inlet valves 172, so that at the end of the filling process, the desired level of the lubricant 140 is reached in each of the lubricant chambers 112, 114, 122, 124.

[0040] The control device 170 also controls the discharge of the lubricant 140 from the lubricant chambers 112, 114, 122, 124 via the line system 162 to the central outlet 160 by controlling the outlet valves 174. Since the vacuum pumps 110, 120 are arranged on top of one another in the vertical direction in the present embodiment, the lubricant 140 flows automatically from the lubricant chambers 112, 114, 122, 124 to the lower central outlet 160 due to gravity after one or more of the outlet valves 174 are opened.

[0041] The discharge of the lubricant 140 from the lubricant chambers 112, 114, 122, 124 can also be carried out sequentially, so that only one of the outlet valves 174 is open at a time. Alternatively, all of the outlet valves 174 or the outlet valves of the vacuum pumps 110, 120 can be opened simultaneously. In order to avoid backflow of the lubricant 140, for example into the lubricant chambers 122, 124 of the second vacuum pump 120, which is lower, a non-return valve 190 is provided between the lubricant chambers 122, 124 and the central outlet 160.

[0042] Figure 2 Exemplary illustration Figure 1 Enlarged partial view of the region of the lubricant chamber 112 of the first vacuum pump 110 in the vacuum apparatus 100 shown. Figure 2 The control mechanism 180, which detects the level of the lubricant 140, is shown in detail. The control mechanism 180 is designed as a float switch and comprises a float 210, which is designed as a ring and completely surrounds a reed contact 220. As a result, the float 210 is always in contact with the lubricant 140 in the lubricant chamber 112. Figure 2 In a cross-sectional view, the float 210 is shown on both sides of the reed contact 220. The float 210 is also located at the surface of the lubricant 140 in the lubricant chamber 112, so that the position of the float 210 in the vertical direction is an indicator of the level of the lubricant 140 in the lubricant chamber 112.

[0043] The float 210 has a permanent magnet 212 which is arranged to activate a reed contact 220 of the control mechanism 180. Once the float 210 reaches the desired level of the lubricant 140 in the lubricant chamber 112, the permanent magnet 212 of the float 210 closes the reed contact 220, thereby outputting a corresponding electrical signal to the control device 170.

[0044] Based on this signal indicating the desired level of the lubricant 140 in the lubricant chamber 112, the control device 170 controls an inlet valve 172 in the pipe system 152 between the central inlet 150 (see Figure 1 ) and the lubricant chamber 112. By means of the control device 170, the inlet valve 172 is controlled in such a way that it is closed when the lubricant 140 in the lubricant chamber 112 reaches the desired level. Thereby, it is ensured that the lubricant chamber 112 is not overfilled with the lubricant 140. In order to adjust the level of the lubricant 140 in the lubricant chamber 112 as desired, the control device 170 can also appropriately operate a corresponding outlet valve 174 of the lubricant chamber 112, which, like the inlet valve 172 and the reed contact 220, is also connected to the control device 170.

[0045] Although Figure 2 only the lubricant chamber 112 of the first vacuum pump 110 is shown and described in detail, the illustration and the above description apply in principle also to the other lubricant chambers 114 of the first vacuum pump 110 and to the other lubricant chambers 122 and 124 of the second vacuum pump 120.

[0046] List of reference signs 100 vacuum device 110 first vacuum pump 112 lubricant chamber 114 lubricant chamber 116 suction chamber 120 second vacuum pump 122 lubricant chamber 124 lubricant chamber 126 suction chamber 130 housing 140 lubricant 150 central inlet 152 pipe system for feeding in lubricant 160 central outlet 162 pipe system for discharging lubricant 170 control device 172 inlet valve 174 outlet valve 176 electrical line 180 control mechanism for the lubricant level 190 check valve 210 float 212 permanent magnet 220 reed contact

Claims

1. A vacuum device (100), comprising: At least two vacuum pumps (110, 120), each having at least one lubricant chamber (112, 114, 122, 124) for containing lubricant (140) for lubricating at least one component of each of the vacuum pumps (110, 120). A central inlet (150) for the lubricant (140), the central inlet communicating with the corresponding lubricant chambers (112, 114, 122, 124) of the vacuum pumps (110, 120), and The central outlet (160) for the lubricant (140) is connected to the corresponding lubricant chambers (112, 114, 122, 124) of the vacuum pumps (110, 120).

2. The vacuum device (100) according to claim 1, wherein, The vacuum device (100) includes a housing (130) surrounding the at least two vacuum pumps (110, 120), and The lubricant chambers (112, 114, 122, 124) of the vacuum pumps (110, 120) have respective inlets and outlets for the lubricant (140), which are arranged inside the housing (130).

3. The vacuum device (100) according to claim 1 or 2, wherein, The vacuum device (100) also includes a control device (170) designed to adjust the proportion of lubricant (140) delivered through the central inlet (150) to the lubricant chambers (112, 114, 122, 124).

4. The vacuum device (100) according to claim 3, wherein, The vacuum device (100) includes valves (172, 174) that are in signal communication with the control device (170), and at least one of the valves (172, 174) corresponds to one of the corresponding lubricant chambers (112, 114, 122, 124) of the vacuum pump (110, 120).

5. The vacuum device (100) according to claim 4, wherein, The control device (170) is designed to switch between the valves (172, 174) such that the lubricant chambers (112, 114, 122, 124) are filled sequentially.

6. The vacuum apparatus (100) according to any one of claims 1 to 5, wherein, Each of the lubricant chambers (112, 114, 122, 124) has a control mechanism (180) for controlling the level of lubricant (140) in each lubricant chamber (112, 114, 122, 124).

7. The vacuum device (100) according to claim 6, wherein, The control mechanism (180) for liquid level includes a float switch.

8. The vacuum device (100) according to claim 7, wherein, The float switch has a reed contact (220).

9. The vacuum apparatus (100) according to any one of claims 1 to 8, wherein, The vacuum pumps (110, 120) each have a rotating shaft. Each of the rotating shafts is equipped with a pump working element, which is disposed within the suction chamber (116, 126) of each of the vacuum pumps (110, 120). Each of the rotating shafts is equipped with at least two bearings, each bearing being connected to one of the lubricant chambers (112, 114, 122, 124).

10. The vacuum device (100) according to claim 9, wherein, The suction chambers (116, 126) of the at least two vacuum pumps (110, 120) are connected to each other.

11. The vacuum apparatus (100) according to any one of claims 1 to 10, wherein, The vacuum pumps (110, 120) include a Roots pump and a screw pump, and The Roots pump is located upstream of the screw pump.

12. The vacuum apparatus (100) according to any one of claims 1 to 11, wherein, One of the vacuum pumps (110, 120) is designed to exhaust gas into the atmosphere.

13. The vacuum apparatus (100) according to any one of claims 1 to 12, wherein, The at least two vacuum pumps (110, 120) are stacked on top of each other in the vertical direction.

14. The vacuum apparatus (100) according to any one of claims 1 to 13, wherein, A check valve (190) is arranged between at least one of the lubricant chambers (112, 114, 122, 124) and the central outlet (160).

15. The vacuum apparatus (100) according to claims 13 and 14, wherein, The corresponding check valve (190) corresponds to the lubricant chamber (112, 114, 122, 124) of one or more vacuum pumps (110, 120), which are arranged vertically below at least one other vacuum pump (110, 120).

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