Vacuum apparatus

Abstract

A vacuum device comprises at least two vacuum pumps (110, 120), each with at least one lubricant chamber (112, 114, 122, 124) for a lubricant used to lubricate at least one component of the respective vacuum pump. The vacuum device also comprises a central inlet (150) for the lubricant, which connects to the respective lubricant chambers of the vacuum pumps, and a central outlet (160) for the lubricant, which also connects to the respective lubricant chambers of the vacuum pumps.

Description

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

[0002] In the vacuum range down to approximately 10 -4 < mbar, two vacuum pumps, such as Roots or screw pumps, can be coupled in series to increase the overall pumping speed of such a pump unit. The first vacuum pump acts as a "booster" for the downstream vacuum pump. This allows the overall pumping speed to be increased several times over compared to the downstream pump.

[0003] Such pump systems with two pumps often comprise a common housing in which the two vacuum pumps are housed, forming a compact unit. However, vacuum pumps for the range up to approximately 10 -4 < mbar usually require an operating fluid or lubricant, for example, to lubricate the bearings of a pump shaft that supports the pumping elements of the vacuum pump. During operation of the pump unit, such vacuum pumps require regular changes of the operating fluid or lubricant to prevent damage to the vacuum pumps.

[0004] If the pumps are enclosed as a compact unit within a common housing, the respective inlet and outlet for the operating fluid or lubricant on the individual vacuum pumps are usually not accessible from outside the housing. To change the operating fluid or lubricant, the housing must be removed in such pump systems and, in some cases, the pump unit must be partially disassembled. This involves increased effort. Even if the inlet and outlet for the operating fluid or lubricant on the respective vacuum pump are accessible from the outside, in known pump systems, changing the operating fluid or lubricant must be carried out separately for each vacuum pump in the system.

[0005] An object of the invention is to provide a vacuum device with at least two vacuum pumps, which allows a simple change of a lubricant for components of the vacuum pumps.

[0006] This object is achieved by a vacuum device having the features of claim 1. Advantageous developments of the invention are specified in the subclaims, the description, and the drawings.

[0007] The vacuum device comprises at least two vacuum pumps, each with at least one lubricant chamber provided for a lubricant for lubricating at least one component of the respective vacuum pump. Furthermore, the vacuum device comprises a central inlet for the lubricant, which communicates with the respective lubricant chambers of the vacuum pumps, and a central outlet for the lubricant, which also communicates with the respective lubricant chambers of the vacuum pumps.

[0008] The at least two vacuum pumps thus have one or more components that require lubrication by means of the lubricant. The vacuum pumps can, for example, comprise Roots pumps or screw pumps, or any combination thereof. In such pumps, a shaft that carries pump-active elements can be mounted on rolling bearings, for example. Such a shaft and the corresponding bearings can thus represent the component of the vacuum pumps that requires lubrication. The lubricant can be, for example, oil.

[0009] The central inlet and the central outlet can each have a fluid connection to all 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 easily supplied to and removed from the respective lubricant chambers of the vacuum pumps, even if the respective inlet and outlet openings of the individual lubricant chambers are not accessible to a user from an outside, i.e., from an external area of ​​the vacuum device.

[0010] The vacuum device thus enables easy lubricant changes without, for example, having to remove or disassemble a housing or other components of the vacuum device. This allows for regular lubricant changes at a specified interval without difficulty. This can extend the service life of the vacuum device, as the minimal effort involved means users will not unnecessarily delay changing the lubricant, as is often the case with conventional systems.

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

[0012] Such respective inlets and outlets for the lubricant are usually not accessible from the outside due to the housing, which would make changing the lubricant difficult, as described above. However, the respective inlets and outlets of the lubricant chambers can be fluidically connected to the central inlet or central outlet of the vacuum device. This allows for reliable filling of the lubricant chambers via the central inlet and reliable draining of the lubricant via the central outlet, even if the respective inlets and outlets of the lubricant chambers are concealed within the housing. Since the at least two vacuum pumps are arranged within the common housing and surrounded by it, the vacuum device as a whole can be designed as a compact unit that requires little installation space.

[0013] According to a further embodiment, the vacuum device further comprises a control device configured to adjust a respective proportion of the lubricant supplied via the central inlet, which is supplied to the respective lubricant chamber. The control device can thus be provided for distributing the lubricant as it is filled into the respective lubricant chambers. The control device can consequently adjust a respective quantity of lubricant that can be supplied to the respective lubricant chamber as the lubricant is filled. In other words, the control device can enable a defined distribution of the lubricant to the respective lubricant chambers so that they can accommodate a respective predefined quantity of lubricant. Conversely, overfilling or underfilling of the respective lubricant chamber can be prevented by means of the control device.

[0014] For this purpose, the vacuum device can comprise valves that are connected to the control device, for example, via signaling, with at least one valve being assigned to each of the lubricant chambers of the vacuum pumps. The valves can be arranged between a central filler neck or the central inlet and the respective lubricant chambers so that the filling of the lubricant chambers with lubricant can be controlled in a defined manner by the control device.

[0015] The control device can further be configured to switch between the valves of the respective lubricant chambers so that they are filled sequentially. Such sequential filling allows the required amount of lubricant to be supplied to the respective lubricant chambers in a direct and controlled manner.

[0016] The lubricant chambers can further each have a control device for the lubricant fill level in the respective lubricant chamber. The respective control device for the lubricant fill level can be functionally and / or signal-wise connected to the control device provided for controlling the filling of the lubricant chambers, so that the control device receives a signal from the respective control device indicating the respective fill level of the lubricant chamber to which the respective control device is assigned.

[0017] The respective level control device for the respective lubricant chamber can prevent this lubricant chamber from being overfilled or underfilled. Thus, the control device can ensure that the desired lubricant level in the respective lubricant chamber is maintained. This can be achieved, for example, by the control device adjusting the respective valves between the central inlet and the respective lubricant chamber based on the signals from the level control devices in such a way that the desired level is neither exceeded nor undercut within predefined limits.

[0018] The control device for the fill level of the respective lubricant chamber can comprise a float switch, which can, for example, have a reed contact. In this way, the fill level control device can be implemented cost-effectively. When a correct fill level is reached during filling of the respective lubricant chamber, a signal from the control device, i.e., a signal from the float switch or reed contact, can cause the control device to close the respective valve associated with the corresponding lubricant chamber, thereby stopping further filling of the lubricant chamber.

[0019] According to a further embodiment, the vacuum pumps each have a rotating shaft. The respective shaft can carry pumping elements arranged in a suction chamber of the respective vacuum pump. At least two bearings can be assigned to the respective shaft, each of which can be connected to one of the lubricant chambers.

[0020] In this embodiment, the vacuum device thus has at least four lubricant chambers, two of which are each assigned to a vacuum pump to supply the at least two bearings of the respective shaft of the vacuum pump with lubricant. The at least four lubricant chambers can in turn have separate inlets and outlets for the lubricant, so that a total of at least four inlets and four outlets of the respective lubricant chambers are connected to the central inlet and the central outlet, respectively. With at least four lubricant chambers in the vacuum device, the effort required to change the lubricant can be significantly reduced if this can be carried out via the central inlet and the central outlet.

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

[0022] For example, the vacuum pumps can 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. Compared to using a screw pump exclusively, this can increase the overall pumping speed of the pump system with the Roots pump and screw pump by approximately an order of magnitude, i.e., by a factor of approximately 10. The pumping speed refers to the volumetric flow rate of the pump per unit of time and is therefore specified, for example, in liters per second.

[0023] Furthermore, one of the vacuum pumps can be configured to exhaust into the atmosphere. In a series connection of several vacuum pumps, this can be the last of the vacuum pumps. Therefore, in this embodiment, the vacuum device no longer requires an additional backing pump, and can instead serve as an efficient and compact backing pump for additional pumps and pump systems, for example, for one or more turbomolecular pumps.

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

[0025] Furthermore, a check valve can be arranged between at least one of the lubricant chambers and the central outlet. By means of such a check valve, a backflow of the lubricant into the lubricant chamber to which the check valve is assigned can be prevented when the lubricant is drained. Such a backflow can occur, for example, when the lubricant is drained from a vacuum pump arranged higher in the vertical direction or from one of its lubricant chambers and flows towards the central outlet, which can be arranged vertically below the vacuum pumps. Without the presence of the check valve, the lubricant would possibly only partially reach the central outlet and could instead flow into one of the lower-lying lubricant chambers.The check valve can thus ensure that the lubricant can only flow towards the central outlet during drainage and cannot enter other lubricant chambers.

[0026] In the case where at least two vacuum pumps are arranged vertically one above the other, a respective check valve can be assigned to the lubricant chambers of one or more vacuum pumps that are arranged vertically below at least one other of the vacuum pumps. A respective check valve can thus be arranged only on the vacuum pump arranged in the lowest position vertically or on all vacuum pumps that are located below the uppermost vacuum pump. The respective check valves can be arranged upstream of the lubricant confluence at or in front of the common central outlet, i.e. between the respective outlet of the lubricant chambers and the central outlet.

[0027] The invention is described below by way of example using advantageous embodiments with reference to the accompanying figures. They show, schematically: Fig. 1a side view of a vacuum device with two vacuum pumps and Fig. 2a detailed view of a lubricant chamber of one of the vacuum pumps of Fig. 1 .

[0028] Fig. 1 schematically shows a vacuum device 100 comprising a first vacuum pump 110 and a second vacuum pump 120. The two vacuum pumps 110, 120 are arranged in a common housing 130, so that the housing 130 completely surrounds 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 in turn arranged on opposite sides of a suction chamber 126 of the second vacuum pump 120.

[0030] The respective lubricant chambers 112, 114, 122, 124 contain a lubricant 140, which is provided for lubricating bearings for a respective shaft (both not shown) of the vacuum pumps 110, 120. During operation of the vacuum pump 110, 120, the respective shaft of the vacuum pumps 110, 120 is driven by a motor (not shown) of the vacuum pumps 110, 120. Active pumping elements (not shown) of the respective vacuum pumps 110, 120 are arranged in the respective suction chamber 116, 126 and connected to the respective shaft to be rotationally driven during operation of the vacuum pumps 110, 120.

[0031] As in Fig. 1As can be seen, the vacuum pumps 110, 120 are arranged vertically one above the other, so that the first vacuum pump 110 is located vertically above the second vacuum pump 120. Furthermore, the suction chambers 116, 126 of the two vacuum pumps 110, 120 are connected to one another, so that the two vacuum pumps 110, 120 are connected in series in terms of vacuum technology. The first vacuum pump 110 therefore performs a boost function for the second vacuum pump 120. As a result, the suction capacity of the pump arrangement with the two vacuum pumps 110, 120 or of the entire vacuum device 100 can be significantly increased compared to the second vacuum pump 120 alone, for example by a factor of 10. The suction capacity refers to the volume throughput of the vacuum pumps 110, 120 per unit of time and is specified, for example, in liters per second.

[0032] Since the two vacuum pumps 110, 120 in the vacuum device 100 are enclosed by the common housing 130, the coupled vacuum pumps 110, 120 form a compact unit in which a pump inlet (not shown) of the first vacuum pump 110 can be connected to a recipient, while a pump outlet of the second vacuum pump 120 can discharge into the atmosphere. This results in a booster pump that can generate a vacuum in the recipient in a range of up to approximately 10 -4 < mbar if the first vacuum pump 110 is designed as a Roots pump and the second vacuum pump 120 as a screw pump.

[0033] During operation of the vacuum device 100, however, the two vacuum pumps 110, 120 require a change of the lubricant 140 at predefined intervals to ensure adequate lubrication of the respective bearings of the vacuum pumps 110, 120 and thus avoid damage to the respective shafts of the vacuum pumps 110, 120. Specifically, the lubricant 140 in the lubricant chambers 112, 114, 122, 124 should be replaced at regular intervals. However, due to the shared housing 130, the respective inlets and outlets of the lubricant chambers 112, 114, 122, 124 are not accessible.

[0034] This means that in known pump systems with two vacuum pumps and a shared housing, the housing must be at least partially removed or disassembled to access the respective inlets and outlets of the lubricant chambers and to replace the lubricant. Since this involves increased effort, changing the lubricant during operation of such a compact pump arrangement with two vacuum pumps and a shared housing is often delayed until a failure of one of the two vacuum pumps occurs. Furthermore, changing the lubricant for each individual vacuum pump also involves increased effort.

[0035] To circumvent these difficulties, the vacuum device 100 according to the invention 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 fluidly connected via a line system 152 to the lubricant chambers 112, 114, 122, 124 of the first vacuum pump 110 and the second vacuum pump 120. Similarly, the lubricant chambers 112, 114, 122, 124 are fluidly connected to the central outlet via a further line system 162. The line system 152 between the central inlet 150 and the respective lubricant chambers 112, 114, 122, 124 is Fig. 1 illustrated with solid lines, while the line system 162 between the lubricant chambers 112, 114, 122, 124 and the central outlet 160 is illustrated with dash-dotted lines.

[0036] The vacuum device 100 further comprises a control device 170, which is designed to control the inlet and outlet of the lubricant 140 into and from the lubricant chambers 112, 114, 122, 124. This includes the control device 170 distributing the lubricant 140 to the lubricant chambers 112, 114, 122, 124. For this purpose, the control device 170 is connected to valves 172, 174, which are arranged in the line system 152 and 162, respectively. Each of the lubricant chambers 112, 114, 122, 124 is assigned an inlet valve 172 and an outlet valve 174.

[0037] The inlet valves 172 are located between the central inlet 150 and a respective inlet of one of the lubricant chambers 112, 114, 122, 124, while the outlet valves 174 are located between a respective one of the lubricant chambers 112, 114, 122, 124 and the central outlet 160. Using the inlet valves 172, the control device 170 adjusts the respective portion of the lubricant 140 that enters the vacuum device 100 via the central inlet 150 and subsequently flows into the respective lubricant chamber 112, 114, 122, 124. When filling the lubricant chambers 112, 114, 122, 124, the control device 170 switches between the valves 172 in such a way that only one of the inlet valves 172 is open at a given time.The inlet valves 172 are thus opened successively for a predetermined period of time, so that during this period only one of the inlet valves is open at a time and all other inlet valves 172 are closed. As a result, the lubricant chambers 112, 114, 122, 124 are filled successively.

[0038] Electrical connections or lines 176 are provided to control the respective valves 172, 174. For the sake of clarity, the lines 176 are Fig. 1 only for the lubricant chamber 114 of the vacuum pump 110. However, it is understood that all inlet valves 172 and all outlet valves 174 are connected to the control device 170 via lines 176.

[0039] Furthermore, a control device 180 for a fill level of the lubricant 140 in the respective lubricant chamber 112, 114, 122, 124 is arranged in each of the lubricant chambers 112, 114, 122, 124. The respective control device 180 for the fill level of the lubricant is in Fig. 2shown in detail and is described in more detail below. The respective monitoring device 180 is also communicatively connected to the control device 170 via lines 176. The control device 170 therefore receives a signal from the respective monitoring device 180 that corresponds to the respective fill level of the lubricant 140 in the respective lubricant chamber 112, 114, 122, 124. Such a signal can, for example, indicate whether a predetermined fill level of the lubricant 140 in the respective lubricant chamber 112, 114, 122, 124 has been reached or not. Based on such a signal, the control device 170 can suitably control the filling of the respective lubricant chambers 112, 114, 122, 124 by means of the inlet valves 172, so that at the end of a filling process, the desired fill level of the lubricant 140 is reached in each of the lubricant chambers 112, 114, 122, 124.

[0040] By controlling the respective outlet valves 174, the control device 170 further controls the discharge of the lubricant 140 from the respective lubricant chambers 112, 114, 122, 124 via the line system 162 toward the central outlet 160. Since the vacuum pumps 110, 120 are arranged vertically one above the other in the present embodiment, the lubricant 140 automatically flows from the respective lubricant chambers 112, 114, 122, 124 to the lower central outlet 160 due to gravity after one or more outlet valves 174 are opened.

[0041] The draining of the lubricant 140 from the lubricant chambers 112, 114, 122, 124 can again be carried out successively by only opening one of the outlet valves 174 at a time. Alternatively, all outlet valves 174 or the outlet valves of a respective one of the vacuum pumps 110, 120 can be opened simultaneously. To prevent backflow of the lubricant 140, for example, into the lubricant chambers 122, 124 of the lower-lying second vacuum pump 120, a check valve 190 is provided between these lubricant chambers 122, 124 and the central outlet 160.

[0042] Fig. 2 shows an example of an enlarged section of the vacuum device 100 of Fig. 1 in the area of ​​the lubricant chamber 112 of the first vacuum pump 110. The control device 180 for the level of the lubricant 140 is in Fig. 2shown in detail. The control device 180 is designed as a float switch and comprises a float 210, which is ring-shaped and completely surrounds a reed contact 220. In the sectional view of Fig. 2 The float 210 is therefore shown on both sides of the reed contact 220. The float 210 is also located on the surface of the lubricant 140 in the lubricant chamber 112, so that the position of the float 210 in the vertical direction represents a measure of the fill level of the lubricant 140 in the lubricant chamber 112.

[0043] The float 210 has a permanent magnet 212, which is provided for actuating a reed contact 220 of the control device 180. As soon as the float 210 reaches a desired fill level of the lubricant 140 in the lubricant chamber 112, the permanent magnet 212 of the float 210 closes the reed contact 220, which thereby outputs a corresponding electrical signal to the control device 170.

[0044] Based on this signal, which indicates the desired fill level of the lubricant 140 in the lubricant chamber 112, the control device 170 controls the inlet valve 172 within the line system 152 between the central inlet 150 (cf. Fig. 1) and the lubricant chamber 112. The control of the inlet valve 172 by means of the control device 170 is such that the inlet valve 172 is closed when the desired fill level of the lubricant 140 in the lubricant chamber 112 is reached. This ensures that the lubricant chamber 112 is not excessively filled with the lubricant 140. In order to adjust the fill level of the lubricant 140 in the lubricant chamber 112 as desired, the control device 170 can also suitably actuate the outlet valve 174, which is assigned to the lubricant chamber 112 and, like the inlet valve 172 and the reed contact 220, is connected to the control device 170.

[0045] Although in Fig. 2Only the lubricant chamber 112 of the first vacuum pump 110 is shown and described in detail, this illustration and the above description also apply analogously to the other lubricant chambers 114, 122 and 124 of the first and second vacuum pumps 110, 120. List of reference symbols

[0046] 100Vacuum device 110First vacuum pump 112Lubricant chamber 114Lubricant chamber 116Pump chamber 120Second vacuum pump 122Lubricant chamber 124Lubricant chamber 126Pump chamber 130Housing 140Lubricant 150Central inlet 152Pipe system for the lubricant inlet 160Central outlet 162Pipe system for the lubricant outlet 170Control device 172Inlet valve 174Outlet valve 176Electrical line 180Control device for the lubricant level 190Check valve 210Float 212Permanent magnet 220Reed contact

Claims

1. Vacuum device (100), comprising at least two vacuum pumps (110, 120), each having at least one lubricant chamber (112, 114, 122, 124) provided for a lubricant (140) for lubricating at least one component of the respective vacuum pump (110, 120), a central inlet (150) for the lubricant (140), which is connected to the respective lubricant chambers (112, 114, 122, 124) of the vacuum pumps (110, 120), and a central outlet (160) for the lubricant (140), which is connected to the respective lubricant chambers (112, 114, 122, 124) of the vacuum pumps (110, 120).

2. Vacuum device (100) according to claim 1, wherein the vacuum device (100) comprises a housing (130) that surrounds the at least two vacuum pumps (110, 120), and the lubricant spaces (112, 114, 122, 124) of the vacuum pumps (110, 120) have a respective inlet and a respective outlet for the lubricant (140) that are arranged within the housing (130).

3. Vacuum device (100) according to claim 1 or 2, wherein the vacuum device (100) further comprises a control device (170) which is designed to adjust a respective proportion of the lubricant (140) supplied via the central inlet (150) which is supplied to the respective lubricant chamber (112, 114, 122, 124).

4. Vacuum device (100) according to claim 3, wherein the vacuum device (100) comprises valves (172, 174) which are signal-connected to the control device (170), and at least one valve (172, 174) is assigned to one of the lubricant chambers (112, 114, 122, 124) of the vacuum pumps (110, 120).

5. Vacuum device (100) according to claim 4, wherein the control device (170) is designed to switch between the valves (172, 174) in such a way that the lubricant chambers (112, 114, 122, 124) are filled one after the other.

6. Vacuum device (100) according to one of claims 1 to 5, wherein the lubricant chambers (112, 114, 122, 124) each have a control device (180) for a fill level of the lubricant (140) in the respective lubricant chamber (112, 114, 122, 124).

7. Vacuum device (100) according to claim 6, wherein the control device (180) for the fill level comprises a float switch.

8. Vacuum device (100) according to claim 7, wherein the float switch comprises a reed contact (220).

9. Vacuum device (100) according to one of claims 1 to 8, wherein the vacuum pumps (110, 120) each have a rotating shaft, the respective shaft carries pump-active elements which are arranged in a suction chamber (116, 126) of the respective vacuum pump (110, 120), and at least two bearings are assigned to the respective shaft, each of which is connected to one of the lubricant chambers (112, 114, 122, 124).

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

11. Vacuum device (100) according to one of claims 1 to 10, wherein the vacuum pumps (110, 120) comprise a Roots pump and a screw pump and the Roots pump is arranged upstream of the screw pump.

12. Vacuum device (100) according to one of claims 1 to 11, wherein one of the vacuum pumps (110, 120) is designed to discharge into the atmosphere.

13. Vacuum device (100) according to one of claims 1 to 12, wherein the at least two vacuum pumps (110, 120) are arranged one above the other in a vertical direction.

14. Vacuum device (100) according to 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. Vacuum device (100) according to claim 13 and 14, wherein a respective non-return valve (190) is associated with the lubricant chambers (112, 114, 122, 124) of one or more vacuum pumps (110, 120) arranged in the vertical direction below at least one other of the vacuum pumps (110, 120).

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