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 rotary lobe or screw pumps, can be coupled in series to increase the overall pumping speed of such a pumping unit. The first vacuum pump acts as a "booster" for the downstream vacuum pump. This allows the overall pumping speed to be increased many times over compared to the pumping speed of the downstream pump.

[0003] Such dual-pump systems often include a common housing that contains the two vacuum pumps, forming a compact unit. However, vacuum pumps for pressures down to approximately 10⁻⁴ mbar usually require a lubricant or operating fluid, for example, to lubricate the bearings of a pump shaft that carries the pumping elements. During operation, these vacuum pumps require regular changes of the lubricant or operating fluid to prevent damage to the pumps.

[0004] When the pumps are enclosed as a compact unit in a common housing, the individual inlet and outlet for the operating fluid or lubricant on each vacuum pump are usually inaccessible from outside the housing. To change the operating fluid or lubricant in such pump systems, the housing must be removed and, in some cases, the pump unit partially disassembled. This is associated with increased effort. Even if the inlet and outlet for the operating fluid or lubricant on each individual vacuum pump are accessible from the outside, the change of operating fluid or lubricant must be carried out separately for each vacuum pump in known pump systems.

[0005] A vacuum device with the features according to the preamble of claim 1 is known from GB 848 785 A.

[0006] FR 3 112 578 A3 describes a rotary vane vacuum pump with two pumping stages, each connected to a common oil reservoir for lubrication.

[0007] US patent 2005 / 0238502 A1 describes a rotary vane vacuum pump with features according to a similar technology.

[0008] WO 2023 / 280660 A1 describes a vacuum device with two vacuum pumps, in which a respective lubricant chamber for a bearing of a shaft is connected to an external oil pump.

[0009] One object of the invention is to create a vacuum device with at least two vacuum pumps that allows for a simple change of lubricant for components of the vacuum pumps.

[0010] This problem is solved by a vacuum device having the features of claim 1. Advantageous embodiments of the invention are specified in the dependent claims, the description, and the drawings.

[0011] The vacuum device comprises at least two vacuum pumps, each with at least one lubrication chamber intended for a lubricant to lubricate at least one component of the respective vacuum pump. Furthermore, the vacuum device comprises a central inlet for the lubricant, which connects to the respective lubricant chambers of the vacuum pumps, and a central outlet for the lubricant, which also connects to the respective lubricant chambers of the vacuum pumps.

[0012] The at least two vacuum pumps thus have one or more components that require lubrication by means of a lubricant. The vacuum pumps can, for example, be rotary lobe pumps or screw pumps, or any combination thereof. In such pumps, a shaft carrying pump-active elements can, for example, be supported by rolling bearings. Such a shaft and the corresponding bearings can therefore constitute the component of the vacuum pumps that requires lubrication. The lubricant can, for example, be oil.

[0013] The central inlet and 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 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 the outside, i.e., from an external area of ​​the vacuum device.

[0014] The vacuum device thus allows for easy lubricant changes without the need to remove or disassemble any housing or other components. This enables regular lubricant changes at predetermined intervals without difficulty. This can extend the service life of the vacuum device, as users will not unnecessarily delay lubricant changes due to the minimal effort involved, unlike with other systems.

[0015] According to one embodiment, the vacuum device comprises a housing that surrounds the at least two vacuum pumps. The lubricant chambers of the at least two vacuum pumps can each have an inlet and an outlet for the lubricant, which are arranged within the housing.

[0016] Such individual inlets and outlets for the lubricant are typically not accessible from the outside due to the housing, which would complicate lubricant changes, as described above. However, the individual inlets and outlets of the lubricant chambers can be fluidically connected to the central inlet and outlet of the vacuum unit, respectively. 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 individual inlets and outlets of the lubricant chambers are concealed within the housing. Since the at least two vacuum pumps are arranged within and surrounded by the common housing, the vacuum unit as a whole can be designed as a compact unit requiring little installation space.

[0017] According to the invention, the vacuum device further comprises a control device configured to adjust the proportion of lubricant supplied via the central inlet that is directed to each lubricant chamber. The control device is thus designed to distribute the lubricant during filling into the respective lubricant chambers. Consequently, the control device sets a specific quantity of lubricant that can be supplied to each lubricant chamber during filling. In other words, the control device enables a defined distribution of the lubricant to the respective lubricant chambers, so that each chamber can hold a predefined quantity of lubricant. Conversely, the control device can prevent overfilling or underfilling of the respective lubricant chamber.

[0018] For this purpose, the vacuum device can include valves that are connected to the control unit, for example via signal transmission, with at least one valve assigned to each of the lubricant chambers of the vacuum pumps. The valves can be arranged between a central filling port or inlet and the respective lubricant chambers so that the filling of the lubricant chambers with lubricant can be precisely controlled by the control unit.

[0019] The control device can further be configured to switch between the valves of the respective lubricant chambers in such a way that they are filled sequentially. This successive filling allows the required quantity of lubricant to be supplied to each lubricant chamber directly and in a controlled manner.

[0020] The lubricant compartments may each also have a monitoring device for the lubricant level in the respective compartment. The respective monitoring device for the lubricant level may be functionally and / or signal-wise connected to the control device intended for controlling the filling of the lubricant compartments, so that the control device receives a signal from the respective monitoring device indicating the respective lubricant level of the compartment to which the respective monitoring device is assigned.

[0021] The level control device for each lubricant chamber prevents overfilling or underfilling. This ensures a desired lubricant level in each chamber. For example, the control unit uses the level control device's signals to adjust valves between the central inlet and each lubricant chamber, ensuring the desired level remains within predefined limits.

[0022] The level control device for the respective lubricant compartment can include a float switch, which may, for example, have a reed contact. This allows for a cost-effective implementation of the level control device. When the correct level is reached during the filling process of the respective lubricant compartment, a signal from the control device—i.e., a signal from the float switch or reed contact—can cause the control unit to close the corresponding valve associated with that lubricant compartment, thereby stopping further filling.

[0023] According to a further embodiment, the vacuum pumps each have a rotating shaft. The respective shaft can carry pump-active elements arranged in a pumping chamber of the respective vacuum pump. At least two bearings can be assigned to each shaft, each of which can be connected to one of the lubricant chambers.

[0024] In this embodiment, the vacuum device thus has at least four lubricant chambers, two of which are assigned to each vacuum pump to supply lubricant to the at least two bearings of the respective vacuum pump shaft. 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 outlet, respectively. With at least four lubricant chambers in the vacuum device, the effort required for changing the lubricant can be significantly reduced if this can be carried out via the central inlet and outlet.

[0025] The pumping chambers of at least two vacuum pumps can be interconnected. The vacuum pumps can thus be coupled in series, so that one pump provides a boost function for the subsequent pump.

[0026] For example, the vacuum pumps can include a rotary lobe pump and a screw pump, with the rotary lobe pump positioned upstream of the screw pump. In this example, the rotary lobe pump can act as a booster pump for the screw pump. Compared to using only a screw pump, this can increase the overall pumping speed of the system with both rotary lobe and screw pumps by approximately one order of magnitude, i.e., by a factor of about 10. Pumping speed refers to the volumetric flow rate of the pump per unit of time and is therefore expressed, for example, in liters per second.

[0027] Furthermore, one of the vacuum pumps can be configured to discharge to 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 a separate backing pump and can instead serve as an efficient and compact backing pump for other pumps and pumping systems, for example, for one or more turbomolecular pumps.

[0028] 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 form. 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 the top and the central outlet, for example, on the bottom of a common housing of the at least two vacuum pumps or the vacuum device.

[0029] Furthermore, a check valve can be arranged between at least one of the lubricant chambers and the central outlet. Such a check valve prevents backflow of lubricant into the lubricant chamber to which it is assigned when the lubricant is drained. Such backflow can occur, for example, when lubricant is drained from a vacuum pump located higher vertically, or from one of its lubricant chambers, and flows towards the central outlet, which may be located vertically below the vacuum pumps. Without the check valve, the lubricant might only partially reach the central outlet and could instead flow into one of the lower lubricant chambers.The non-return valve can thus ensure that the lubricant only flows towards the central outlet during draining and cannot enter other lubricant chambers.

[0030] In cases where at least two vacuum pumps are arranged vertically one above the other, a check valve can be assigned to the lubricant chambers of one or more vacuum pumps located vertically below at least one other vacuum pump. A check valve can therefore be located either on the vacuum pump in the lowest vertical position or on all vacuum pumps located below the uppermost vacuum pump. The check valves can be positioned upstream of the lubricant convergence point, either at or before the common central outlet, i.e., between the respective outlet of the lubricant chambers and the central outlet.

[0031] The invention is described below by way of example with reference to advantageous embodiments and the accompanying figures. These show, schematically: Fig. 1 a side view of a vacuum device with two vacuum pumps and Fig. 2 a detailed view of a lubricant chamber of one of the vacuum pumps. Fig. 1 .

[0032] Fig. 1 Figure 1 schematically shows a vacuum device 100 comprising a first vacuum pump 110 and a second vacuum pump 120. The two vacuum pumps 110 and 120 are arranged in a common housing 130, such that the housing 130 completely surrounds both the first vacuum pump 110 and the second vacuum pump 120. The first vacuum pump 110 is, for example, a rotary lobe pump, while the second vacuum pump 120 is, for example, a screw pump.

[0033] 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 pumping 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 again arranged on opposite sides of a pumping chamber 126 of the second vacuum pump 120.

[0034] The respective lubrication chambers 112, 114, 122, 124 contain a lubricant 140, which is intended for the lubrication of bearings for a respective shaft (both not shown) of the vacuum pumps 110, 120. During operation of the vacuum pumps 110, 120, the respective shaft is driven by a motor (not shown) of the vacuum pumps 110, 120.

[0035] Pump-active elements (not shown) of the respective vacuum pump 110, 120 are arranged in the respective pumping chamber 116, 126 and connected to the respective shaft in order to be driven in rotation during the operation of the vacuum pumps 110, 120.

[0036] As in Fig. 1As can be seen, the vacuum pumps 110 and 120 are arranged vertically one above the other, such that the first vacuum pump 110 is located vertically above the second vacuum pump 120. Furthermore, the pumping chambers 116 and 126 of the two vacuum pumps 110 and 120 are connected to each other, so that the two vacuum pumps 110 and 120 are connected in series. The first vacuum pump 110 therefore provides a boost function for the second vacuum pump 120. This significantly increases the pumping speed of the pump arrangement with the two vacuum pumps 110 and 120, or of the entire vacuum device 100, compared to the second vacuum pump 120 alone, for example by a factor of 10. The pumping speed refers to the volumetric flow rate of the vacuum pumps 110 and 120 per unit of time and is specified, for example, in liters per second.

[0037] 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 receiver, while a pump outlet of the second vacuum pump 120 can discharge to the atmosphere. This results in a booster pump that can generate a vacuum in the receiver in a range down to approximately 10⁻⁴ mbar if the first vacuum pump 110 is designed as a rotary lobe pump and the second vacuum pump 120 as a screw pump.

[0038] During operation of the vacuum device 100, the two vacuum pumps 110 and 120 require a change of lubricant 140 at predefined intervals to ensure sufficient lubrication of the respective bearings of the vacuum pumps 110 and 120 and thereby prevent damage to the respective shafts of the vacuum pumps 110 and 120. Specifically, the lubricant 140 in the lubricant chambers 112, 114, 122, and 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, and 124 are not accessible.

[0039] This means that in known pump systems with two vacuum pumps and a common housing, the housing must be at least partially removed or disassembled to access the respective inlets and outlets of the lubricant reservoirs and to change the lubricant. Since this involves increased effort, in the operation of such a compact pump arrangement with two vacuum pumps and a common housing, lubricant changes are often postponed until one of the two vacuum pumps fails. Furthermore, changing the lubricant in each individual vacuum pump is also more complex.

[0040] 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 filling port 150 is fluidically 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 fluidically 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 in Fig. 1 illustrated with solid lines, while the piping system 162 between the lubricant chambers 112, 114, 122, 124 and the central outlet 160 is illustrated with dashed lines.

[0041] 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 out of 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 and 174, which are arranged in the piping 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.

[0042] The inlet valves 172 are located between the central inlet 150 and each inlet of one of the lubricant chambers 112, 114, 122, 124, while the outlet valves 174 are located between each of the lubricant chambers 112, 114, 122, 124 and the central outlet 160. The control device 170 uses the inlet valves 172 to regulate the proportion of lubricant 140 that enters the vacuum device 100 via the central inlet 150 and then 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 at any given time only one of the inlet valves 172 is open.The inlet valves 172 are thus opened successively for a predetermined period, so that during this period only one of the inlet valves is open at any given time and all other inlet valves 172 are closed. This allows the lubrication chambers 112, 114, 122, 124 to be filled successively.

[0043] Electrical connections or lines 176 are provided for controlling the respective valves 172 and 174. For clarity, the lines 176 are shown in Fig. 1 The diagram shows only the lubricant chamber 114 of the vacuum pump 110. It is understood, however, that all inlet valves 172 and all outlet valves 174 are connected to the control unit 170 via the lines 176.

[0044] Furthermore, each of the lubricant compartments 112, 114, 122, 124 is equipped with a monitoring device 180 for the lubricant level 140. The respective monitoring device 180 for the lubricant level is located in Fig. 2The details are shown below and described in more detail. Each control unit 180 is also communicatively connected to the control unit 170 via lines 176. The control unit 170 therefore receives a signal from the respective control unit 180, corresponding to the current 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 appropriately 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.

[0045] By means of a control of the respective outlet valves 174, the control device 170 further controls the draining of the lubricant 140 from the respective lubricant chambers 112, 114, 122, 124 via the piping system 162 towards the central outlet 160. Since the vacuum pumps 110, 120 are arranged vertically one above the other in the present embodiment, the lubricant 140 flows automatically 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 have been opened.

[0046] The draining of the lubricant 140 from the lubricant chambers 112, 114, 122, 124 can be carried out successively by opening only one of the outlet valves 174 at a time. Alternatively, all outlet valves 174 or the outlet valves of each 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.

[0047] Fig. 2 shows an enlarged section of the vacuum device 100 as an example. Fig. 1 in the area of ​​the lubricant chamber 112 of the first vacuum pump 110. The control device 180 for the lubricant level 140 is located 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. Furthermore, the float 210 is 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.

[0048] The float 210 has a permanent magnet 212, which is intended to actuate a reed contact 220 of the control device 180. As soon as the float 210 reaches a desired level of 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.

[0049] 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 piping system 152 between the central inlet 150 (see Fig. 1) and the lubricant chamber 112. The inlet valve 172 is controlled by the control device 170 such that the inlet valve 172 closes when the desired level of lubricant 140 in the lubricant chamber 112 is reached. This ensures that the lubricant chamber 112 is not overfilled with lubricant 140. To adjust the level of lubricant 140 in the lubricant chamber 112 as desired, the control device 170 can also actuate the outlet valve 174, which is associated with the lubricant chamber 112 and, like the inlet valve 172 and the reed contact 220, is connected to the control device 170.

[0050] Although in Fig. 2Although only the lubricant compartment 112 of the first vacuum pump 110 is shown and described in detail, this illustration and the preceding description also apply analogously to the further lubricant compartments 114, 122 and 124 of the first and the second vacuum pump 110, 120. Reference symbol list

[0051] 100 Vacuum device 110 First vacuum pump 112 Lubricant chamber 114 Lubricant chamber 116 Pumping chamber 120 Second vacuum pump 122 Lubricant chamber 124 Lubricant chamber 126 Pumping chamber 130 Housing 140 Lubricant 150 Central inlet 152 Lubricant inlet piping system 160 Central outlet 162 Lubricant outlet piping system 170 Control device 172 Inlet valve 174 Outlet valve 176 Electrical line 180 Lubricant level control device 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) which is 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) that is in connection with the respective lubricant chambers (112, 114, 122, 124) of the vacuum pumps (110, 120), and a central outlet (160) for the lubricant (140) that is in connection with the respective lubricant chambers (112, 114, 122, 124) of the vacuum pumps (110, 120), characterized in that the vacuum device (100) further comprises a control device (170) which is configured to set a respective portion of the lubricant (140) fed via the central inlet (150), said portion being fed to the respective lubricant chamber (112, 114, 122, 124).

2. A vacuum device (100) according to claim 1, wherein the vacuum device (100) comprises a housing (130) which surrounds the at least two vacuum pumps (110, 120), and the lubricant chambers (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. A vacuum device (100) according to claim 1 or 2, wherein the vacuum device (100) comprises valves (172, 174), which are in connection with the control device (170) in a signal technical manner, 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) in each case.

4. A vacuum device (100) according to claim 3, wherein the control device (170) is configured to switch between the valves (172, 174) such that the lubricant chambers (112, 114, 122, 124) are filled after one another.

5. A vacuum device (100) according to any one of the claims 1 to 4, wherein the lubricant chambers (112, 114, 122, 124) each have a control device (180) for a filling level of the lubricant (140) in the respective lubricant chamber (112, 114, 122, 124).

6. A vacuum device (100) according to claim 5, wherein the control device (180) comprises a float switch for the filling level.

7. A vacuum device (100) according to claim 6, wherein the float switch has a reed contact (220).

8. A vacuum device (100) according to any one of the claims 1 to 7, 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 and are each in connection with one of the lubricant chambers (112, 114, 122, 124).

9. A vacuum device (100) according to claim 8, wherein the suction chambers (1116, 126) of at least two of the vacuum pumps (110, 120) are connected to one another.

10. A vacuum device (100) according to any one of the claims 1 to 9, 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.

11. A vacuum device (100) according to any one of the claims 1 to 10, wherein one of the vacuum pumps (110, 120) is configured to discharge to atmosphere.

12. A vacuum device (100) according to any one of the claims 1 to 11, wherein the at least two vacuum pumps (110, 120) are arranged above one another in a vertical direction.

13. A vacuum device (100) according to any one of the claims 1 to 12, wherein a check valve (190) is arranged between at least one of the lubricant chambers (112, 114, 122, 124) and the central outlet (160).

14. A vacuum device (100) according to claim 12 and 13, wherein a respective check valve (190) is assigned to the lubricant chambers (112, 114, 122, 124) of one or more vacuum pumps (110, 120) which are arranged below at least one other of the vacuum pumps (110, 120) in the vertical direction.

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