Vent valve and vacuum pump fitted with vent valve

Abstract

To provide a vent valve for a vacuum pump in consideration of a problem with a conventional technique.SOLUTION: A vent valve 10 opens and closes a vent opening in a housing of a vacuum pump 111, and comprises a valve housing 12 and a valve element 14. A through hole 16 penetrates the valve housing. The through hole extends from a first axial end surface 17 of the valve housing to a second axial end surface 18, and comprises a female thread 20. The valve element comprises a screw body part 22 comprising a male thread. The valve element is screwed to the female thread of the through hole by the male thread. The screw body part comprises a rotation drive device 28 for operating the valve element, in a first end part 25, and comprises a valve plate 30 in a second end part 26 on the side opposite to the first end part. The valve plate is in contact with the second end surface of the valve housing in order to seal the through hole at a first axial position of the valve element. The valve plate has an interval A from the second end surface at the second axial position of the valve element.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to a ventilation valve that can selectively open and close a ventilation opening formed in a housing of a vacuum pump, particularly a turbo molecular vacuum pump. Furthermore, the present invention relates to a vacuum pump equipped with such a ventilation valve.

Background Art

[0002] For example, vacuum pumps such as turbo molecular vacuum pumps often have ventilation openings, and through the ventilation openings, the pump stages existing in the pump or the pump housing can be ventilated with the air coming from the atmosphere. Thereby, for example, it is possible to accurately affect the rotational speed of the rotor of the pump stage.

[0003] In currently used vacuum pumps, the ventilation opening is usually closed by a simple ventilation screw. The ventilation screw can be manually loosened via a rotation drive device in the form of a screw head, and thus the ventilation opening is opened. Moreover, at this time, the ventilation screw is completely unscrewed from the ventilation opening, and in this case, there is a risk of falling into the equipment of the pump operator. In the worst case, the ventilation screw can no longer be found, and as a result, the equipment stops until a new ventilation screw is provided.

[0004] Another problem is that the ventilation screw may tilt when being screwed back into the ventilation opening again, which may in some cases lead to damage to the thread of the ventilation opening.

Summary of the Invention

Problems to be Solved by the Invention

[0005] Therefore, the underlying problem of the present invention is to provide a ventilation valve for a vacuum pump, particularly a turbo molecular vacuum pump, in consideration of the aforementioned problems.

Means for Solving the Problems

[0006] This problem is solved by a vent valve for opening and closing the vent opening of a vacuum pump, in particular a turbomolecular vacuum pump, where the vent valve excels in the features of claim 1.

[0007] Unlike a conventional vent screw, this vent valve mainly consists of two components, namely a valve housing and a valve element. In this case, the valve element is non - removably accommodated by the valve housing, while the valve housing itself is configured to be accommodated in the vent opening of the vacuum pump. Specifically, in this case, a through - hole penetrates the valve housing. The through - hole connects two end faces of the valve housing that are opposite to each other, namely the first axial end face and the second axial end face on the side opposite to the first axial end face. The valve element is a threaded body with a male thread, and through the male thread, the valve element is screwed into the female thread formed in the through - hole of the valve housing. Therefore, by rotating the valve element, the axial position of the valve element relative to the valve housing can be changed.

[0008] Similar to a conventional vent screw, the threaded body also has a rotation drive device, for example in the form of a screw head, at the first end. Through the rotation drive device, the valve element can be rotated manually, and thereby the axial position of the valve element relative to the valve housing can be changed. On the other hand, at the other end, the threaded body has a valve plate integrally formed with it. The valve plate abuts at least indirectly against the second axial end face of the housing at the first axial position of the valve element, thereby tightly closing the through - hole in this way. In contrast, at the second axial position of the valve element, the valve plate is spaced from the second end face. Therefore, at the second axial position, the through - hole is not closed by the valve plate, so based on the gap between the female thread of the through - hole and the male thread of the threaded body, air coming from the atmosphere can flow through the vent valve into the interior of the pump.

[0009] The valve plate is located inside the vacuum pump at the end of the valve plate that is opposite to the rotational drive device of the threaded body portion, and thus in a state incorporated into the vent opening of the vacuum pump. As a result, the valve element will not accidentally become unscrewed from the valve housing and thus fall into the equipment of the pump operator. Rather, when the valve element is "unscrewed", at that time, the valve plate abuts against the second axial end face of the valve housing at the first axial position of the valve element, and this prevents the valve element from being further unscrewed from the valve housing.

[0010] Hereinafter, preferred embodiments of the present invention will be described. Other embodiments may be apparent from the dependent claims, the description of the drawings, and the drawings themselves.

[0011] Based on the previously described thread play, at the second axial position of the valve element, air coming from the atmosphere can flow into the vacuum pump through the through-hole of the valve housing. However, a vent valve is fitted into the vent opening of the vacuum pump, and therefore, based purely on the thread play, any possible air flow for venting the vacuum pump is restricted. According to another embodiment, an axial channel is formed in the threaded body portion that is aligned in the substantially axial or longitudinal direction of the threaded body portion. The axial channel realizes a fluid connection through the threaded body portion for venting the vacuum pump only at the second axial position. On the other hand, the mentioned axial channel interrupts the air flow into the interior of the vacuum pump at the first axial position of the valve element.

[0012] The axial channel may be, for example, a groove extending axially. The groove extends along the threaded body portion between the first end of the threaded body portion and the valve plate at the outer peripheral portion. Thus, the groove mentioned intersects to some extent with the threads of the male thread of the threaded body portion. When the valve element is in its first axial position, at the first axial position, since the valve plate abuts at least indirectly against the second axial end face of the valve housing, based on the fact that the valve plate already seals the through hole, the flow of fluid through the axial channel in the form of a groove on the long extending surface is impossible. In contrast, at the second axial position of the valve element, the air coming from the periphery can flow into the pump through the axial channel to ventilate the pump. At this time, the flow cross section is not restricted by the threads.

[0013] Moreover, the axial channel may be a hole formed inside the threaded body portion. This hole extends from the first end of the threaded body portion towards the second end of the threaded body portion and exits from the threaded body portion adjacent to the valve plate there. Thus, in this embodiment, the axial channel extends slightly obliquely with respect to the longitudinal axis of the threaded body portion, whereby the axial channel may exit laterally from the threaded body portion at the second end of the threaded body portion.

[0014] According to a preferred embodiment, the axial channel may be configured as a pocket hole having an open end formed at a first end of the threaded body and a closed end located at a second end of the threaded body. In this embodiment, the axial channel may extend exactly parallel to, preferably along, the central axis of the threaded body. In this embodiment, at least one radial hole directed substantially radially, preferably exactly radially, may be further formed in the threaded body to realize a fluid flow through the axial channel. The radial hole branches from the pocket hole and exits the threaded body at or adjacent to the second end of the threaded body. Thus, at the second axial position of the valve element, air coming from the atmosphere can flow through the pocket hole and the radial hole branching from the pocket hole into the interior of the vacuum pump to which the vent valve is attached. That is, at the second axial position of the valve element, since at least one radial hole opens into the space by which the valve plate is spaced from the second end face at the second axial position of the valve element, air coming from the atmosphere can flow into the interior of the pump through this space.

[0015] According to another embodiment, in order to enable realization of a plurality of ventilation situations with various volume flows, a first radial hole directed substantially radially and at least one second radial hole directed substantially radially are formed in the threaded body. In this case, it may be contemplated that the first radial hole is located closer to the valve plate than the second radial hole as a whole. Thus, the first radial hole exits the threaded body closer to the valve plate than the second radial hole.

[0016] Therefore, at the second axial position of the valve element, the first radial hole opens into the space that the valve plate has relative to the second end face of the valve housing at the second axial position of the valve element, in the manner described above. At this second axial position of the valve element, the opening of the second radial hole is still located in the thread region of the internal threaded hole in the valve housing, so there is no or only a small volume flow rate that can pass through the second radial hole. Therefore, at the second axial position of the valve element, the interior of the pump is fluidly connected to the external atmosphere solely via the first radial hole that branches off from the pocket hole and the pocket recess. In contrast, in another ventilation situation, a larger volume flow rate should be achieved. Therefore, the valve element can be further screwed into the interior of the pump, so that the opening of the second radial hole is also located in the space between the valve plate and the second axial end face of the valve housing. Therefore, at such a third axial position of the valve element, the external atmosphere is fluidly connected to the interior of the pump via two radial channels. Therefore, assuming that the flow cross-section of the pocket recess is not smaller than the smaller diameter of the two radial holes, a larger volume flow rate can be achieved at the third axial position of the valve element than at the second axial position of the valve element.

[0017] In order to accurately achieve various fluid situations where the volume flow rate increases, according to another embodiment, it can be contemplated that the aperture diameter of the second radial hole is larger than the aperture diameter of the first radial hole. In this case, since the aperture diameter of the second radial hole is not larger than the aperture diameter of the pocket recess, at the third axial position where the two radial holes open into the space between the valve plate and the second axial end face of the valve housing, the achievable volume flow rate through the two radial holes is larger than that at the second axial position of the valve element where the volume flow rate can essentially only pass through the first radial hole.

[0018] The second end of the threaded body where the two radial holes are located is positioned inside the vacuum pump when assembled to the vacuum pump. Thus, from the outside, it cannot be recognized whether the openings of the respective radial holes are already open or are still closed by the valve housing. According to another embodiment, the vent valve has a locking mechanism that acts or can be contemplated to act between the valve housing and the valve shaft when the distance between the valve plate and the second axial end face of the valve housing reaches a predetermined size. In this case, the distance of the predetermined size is dimensioned such that at this position, the first radial hole opens into the distance between the valve plate and the second axial end face of the valve housing and thus can no longer be closed by the valve housing. In this case, the locking mechanism may be formed inside the valve housing, for example, by a radially spring-biased ball. The ball is pressed against the male thread of the valve shaft by spring biasing. In the region of the male thread of the valve shaft, a dot-shaped recess in the form of a depression is formed, and the ball engages in the recess when the distance of the predetermined size is reached and thus when the second axial position of the valve element is reached. Thus, when the second axial position of the valve element is reached, the operator receives a tactile feedback of reaching the second axial position of the valve element as the ball snaps into the recess.

[0019] Based on the fact that the valve plate abuts against the second axial end face of the valve housing at the first axial position of the valve element, it can be ensured that no fluid flow can occur through the ventilation valve, and the through-hole transitions to the second axial end face of the valve housing via the conical recess, provided that the valve plate has a frustoconical portion formed complementarily to the conical recess on the side facing the second axial end face, and this frustoconical portion is received by the conical recess at the first axial position of the valve element, and when abutting against the conical recess, the valve element can be particularly reliably sealed against the valve housing. Thus, when the valve element moves to its first axial position, the seal provided on the valve plate can be drawn into the circumferential gap of the cone between the conical recess and the frustoconical portion of the valve plate, thereby particularly reliably ensuring that no adverse flow can occur through the ventilation valve at the first axial position.

[0020] The seal already described above may, according to a preferred embodiment, be a ring seal supported on the radially outer side of the frustoconical portion on the side where the valve plate faces the second axial end face. The ring seal may preferably be a ring seal vulcanized in contact with a steel support ring concentric to the ring seal. Such a seal is also known as a Usit ring, in which case the steel support ring is used to prevent overloading of the elastic material constituting the ring seal.

[0021] According to yet another embodiment, it may be contemplated that the threaded body has, at its second end, an encircling ring groove adjacent to the valve plate and having a groove depth that matches the thread height of the male thread of the threaded body or is slightly greater than the thread height. In this case, when the first radial hole opens into the ring groove mentioned, the first radial hole may thus be formed directly adjacent to the valve plate and, in some cases, its frustoconical portion in the first threaded body, without the need for the male thread of the threaded body to extend up to the valve plate. Thus, the portion of the threaded body provided with the radial hole may be received by the through-hole of the valve housing without colliding with the thread of the through-hole.

[0022] According to another embodiment, in order to enable intuitive operation of the ventilation valve, it can be contemplated that the male thread of the threaded body and the female thread of the valve housing are configured as left-handed threads. In contrast, if the threads are configured as right-handed threads, in order to open the ventilation valve, the valve element must be rotated clockwise as it normally does when closing the closing mechanism. In contrast, if the threads mentioned are configured as left-handed threads, in order to open the ventilation valve, the valve element needs to be rotated counterclockwise as it normally does in the closing mechanism. Therefore, when the operator cannot rotate the valve element further clockwise, the operator can confirm that the ventilation valve is closed.

[0023] The valve plate is preferably formed integrally with the valve element or the threaded body and abuts against the second axial end face of the valve housing at the first axial position of the valve element. Therefore, within the assembly range of the ventilation valve, the valve element needs to screw the first end of the threaded body into the through hole of the valve housing with the first end as the leading end. To enable this, the rotation drive device is a screw head, and the screw head is attached as a separate part to the first end of the threaded body only after the valve element is screwed into the valve housing. Therefore, the screw head is not formed integrally with the threaded body to realize the assembly of the ventilation valve according to the present invention.

[0024] According to another embodiment, a vent valve can be attached to the vent opening of the vacuum pump. In this case, the valve housing has a male thread, and through the male thread, the male thread and thus the vent valve can be screwed into the female thread of the vent opening of the vacuum pump. In this case, as a rotation drive device, the valve housing has a regular polygonal structure, preferably with a hexagonal cross-section like a nut, between the male thread of the valve housing and the first axial end face. In this case, the mentioned polygonal structure forms a ring shoulder aligned in the radial direction facing the male thread, and the ring shoulder is tightly clamped to the valve housing when the valve housing is screwed into the vent opening. In this case, preferably, the ring shoulder supports a ring seal. In this case, in particular, it is contemplated that the mentioned ring seal is a Usit ring seal, and in this case, the ring seal is vulcanized to a concentric steel support ring with respect to the ring seal.

[0025] According to another aspect of the present invention, furthermore, a vacuum pump, in particular a turbomolecular vacuum pump, which is excellent in the features of claim 15 is presented for the first time. The vacuum pump has a housing, at least one pump stage is present in the housing, a vent opening is formed in the housing, the vent opening communicates with at least one pump stage, and the vent opening houses the valve housing of a vent valve formed according to one of claims 1 to 14.

[0026] Hereinafter, the present invention will be described with reference to the accompanying drawings based on exemplary advantageous embodiments.

Brief Description of the Drawings

[0027]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 7a

Figure 8

Mode for Carrying Out the Invention

[0028] The turbo molecular pump 111 shown in FIG. 1 has a pump intake port 115 surrounded by an intake flange 113. A recipient (not shown) may be connected to the pump intake port 115 in a manner known per se. The gas arriving from the recipient is sucked in from the recipient through the pump intake port 115 and can be pumped through the pump to the pump exhaust port 117.

[0029] An auxiliary vacuum pump such as a rotary vane pump may be connected to the pump exhaust port 117. The intake flange 113 forms the upper end of the housing 119 of the vacuum pump in the orientation of the vacuum pump according to FIG. 1. The housing 119 has a lower part 121. An electronics housing 123 is arranged laterally on the lower part 121. The electronics housing 123 houses electrical and / or electronic components of the vacuum pump 111 for operating, for example, an electric motor 125 (see also FIG. 3) arranged within the vacuum pump. The electronics housing 123 is provided with a plurality of connection parts 127 for accessories. Further, a data interface 129 (for example, one compliant with the RS485 standard) and a current supply connection part 131 are arranged on the electronics housing 123.

[0030] There are also turbo molecular pumps that are connected to external drive electronics without having this type of attached electronics housing.

[0031] In the housing 119 of the turbo molecular pump 111, an intake port 133 for ventilation is provided, particularly in the form of a ventilation valve. Through the intake port 133 for ventilation, the vacuum pump 111 can be ventilated. In the region of the lower part 121, further above it, a seal gas connection part 135 (also referred to as a purge gas connection part) is arranged. Through the seal gas connection part 135, purge gas can be fed into the motor chamber 137 in order to protect the electric motor 125 (see, for example, FIG. 3) against the gas pumped by the pump. In the motor chamber 137, the electric motor 125 is accommodated in the vacuum pump 111. In the lower part 121, further above it, two coolant connection parts 139 are arranged. In this case, one coolant connection part is provided as an intake port for the coolant, and the other coolant connection part is provided as an exhaust port. The coolant can be introduced into the vacuum pump for cooling purposes. Another turbo molecular vacuum pump (not shown) that exists is operated exclusively in an air-cooled manner.

[0032] Since the lower surface 141 of the vacuum pump can be used as a base, the vacuum pump 111 can be operated vertically with reference to the lower surface 141. Moreover, the vacuum pump 111 can be fixed to the recipient via the intake flange 113 and thus can be operated in a so-called suspended state. Further, the vacuum pump 111 may be configured to be operable even when it is oriented in a direction different from that shown in FIG. 1. It is also possible to realize a form of the vacuum pump in which the lower surface 141 is arranged not downward but horizontally or upward. In this case, in principle, any angle is conceivable.

[0033] Another turbo molecular vacuum pump (not shown) that exists and is larger than the particularly shown pump cannot be operated vertically.

[0034] On the lower surface 141 shown in FIG. 2, various screws 143 are further arranged. By these screws 143, the components of the vacuum pump, which are not specified in detail here, are fixed to each other. For example, the bearing cover 145 is fixed to the lower surface 141.

[0035] At 141 below, a fixing hole 147 is further arranged. Through the fixing hole 147, the pump 111 can be fixed to, for example, the installation surface. This is impossible in the case of another existing turbo molecular vacuum pump (not shown) that is larger than the specifically illustrated pump.

[0036] From FIG. 2 to FIG. 5, a coolant pipeline 148 is shown. In the coolant pipeline 148, the coolant introduced and led out through the coolant connection part 139 can circulate.

[0037] As shown in the cross-sectional views from FIG. 3 to FIG. 5, the vacuum pump has a plurality of process gas pump stages. The process gas pump stages are for pumping the process gas acting on the pump intake port 115 to the pump exhaust port 117.

[0038] Inside the housing 119, a rotor 149 is arranged. The rotor 149 has a rotor shaft 153 that can rotate about the rotation axis 151.

[0039] The turbo molecular pump 111 has a plurality of turbo molecular pump stages connected in series with each other so as to exert a pumping action. The turbo molecular pump stages have a plurality of radial moving blades 155 fixed to the rotor shaft 153 and a plurality of stationary blades 157 arranged between the moving blades 155 and fixed inside the housing 119. In this case, one moving blade 155 and one adjacent stationary blade 157 form one turbo molecular pump stage. The stationary blades 157 are held at a desired axial interval from each other by a spacer ring 159.

[0040] The vacuum pump further has Holweck pump stages arranged inside and outside each other in the radial direction and connected in series with each other so as to exert a pumping action. There exists another turbo molecular vacuum pump (not shown) that does not have Holweck pump stages.

[0041] The rotor of the Holbeck pump stage has a rotor hub 161 disposed on the rotor shaft 153, and two cylindrical side surface-like Holbeck rotor sleeves 163, 165 fixed to and supported by the rotor hub 161. The Holbeck rotor sleeves 163, 165 are oriented coaxially with respect to the rotation axis 151 and engage with each other inside and outside in the radial direction. Two cylindrical side surface-like Holbeck stator sleeves 167, 169 are further provided. The Holbeck stator sleeves 167, 169 are likewise oriented coaxially with respect to the rotation axis 151 and engage with each other inside and outside when viewed in the radial direction.

[0042] The pumping surface of the Holbeck pump stage is formed by the side surfaces, that is, by the inner and / or outer side surfaces in the radial direction of the Holbeck rotor sleeves 163, 165 and the Holbeck stator sleeves 167, 169. The inner side surface in the radial direction of the outer Holbeck stator sleeve 167 faces the outer side surface in the radial direction of the outer Holbeck rotor sleeve 163 while forming a radial Holbeck gap 171, and together with this outer side surface, forms the first Holbeck pump stage following the turbomolecular pump. The inner side surface in the radial direction of the outer Holbeck rotor sleeve 163 faces the outer side surface in the radial direction of the inner Holbeck stator sleeve 169 while forming a radial Holbeck gap 173, and together with this outer side surface, forms the second Holbeck pump stage. The inner side surface in the radial direction of the inner Holbeck stator sleeve 169 faces the outer side surface in the radial direction of the inner Holbeck rotor sleeve 165 while forming a radial Holbeck gap 175, and together with this outer side surface, forms the third Holbeck pump stage.

[0043] A channel extending in the radial direction may be provided at the lower end of the Holbeck lotus sleeve 163. Through the channel, the Holbeck gap 171 located radially outside is connected to the central Holbeck gap 173. A channel extending in the radial direction may be further provided at the upper end of the inner Holbeck stator sleeve 169. Through the channel, the central Holbeck gap 173 is connected to the Holbeck gap 175 located radially inside. As a result, a plurality of Holbeck pump stages engaging with each other inside and outside are connected in series with each other. A connection channel 179 leading to the exhaust port 117 may be further provided at the lower end of the Holbeck rotor sleeve 165 located radially inside.

[0044] The surfaces of the Holbeck stator sleeves 167 and 169 that exhibit the aforementioned pumping action each have a plurality of Holbeck grooves that extend axially while spirally orbiting around the axis of rotation 151. On the other hand, the opposing side surfaces of the Holbeck rotor sleeves 163 and 165 are formed smoothly and send the gas for the operation of the vacuum pump 111 forward in the Holbeck grooves.

[0045] For the rotatable shaft support of the rotor shaft 153, a rolling bearing 181 is provided in the region of the pump exhaust port 117, and a permanent magnet type magnetic bearing 183 is provided in the region of the pump intake port 115.

[0046] In the region of the rolling bearing 181, a conical splash nut 185 is provided on the rotor shaft 153. The splash nut 185 has an outer diameter that increases towards the rolling bearing 181. The splash nut 185 is in sliding contact with at least one scraping member of the working medium storage part. In another turbo molecular vacuum pump (not shown) that exists, a splash screw may be provided instead of the splash nut. As a result, various configurations are achievable, and in the above relationship, the term "splash tip" is also used.

[0047] The working medium storage unit has a plurality of absorbent disks 187 stacked vertically. These disks 187 are impregnated with a working medium for the rolling bearing 181, for example, a lubricant.

[0048] During the operation of the vacuum pump 111, the working medium is transmitted from the working medium storage unit to the rotating splash nut 185 through the scraping member by capillary action, and then, based on centrifugal force, along the splash nut 185, towards the rolling bearing 181 in the direction of the increasing outer diameter of the splash nut 185. There, for example, the lubrication function is fulfilled. The rolling bearing 181 and the working medium storage unit are surrounded in the vacuum pump by the tank-shaped insert 189 and the bearing cover 145.

[0049] The permanent magnet type magnetic bearing 183 has a bearing half 191 on the rotor side and a bearing half 193 on the stator side. These each have one ring stack, and the ring stack consists of a plurality of rings 195, 197 of permanent magnets stacked axially one above the other. The ring magnets 195, 197 face each other while forming a radial bearing gap 199 therebetween. In this case, the rotor-side ring magnet 195 is arranged radially outward, and the stator-side ring magnet 197 is arranged radially inward. The magnetic field existing within the bearing gap 199 causes a magnetic repulsive force between the ring magnets 195, 197. That repulsive force realizes the radial shaft support of the rotor shaft 153. The rotor-side ring magnet 195 is supported by a support portion 201 of the rotor shaft 153. The support portion 201 surrounds the ring magnet 195 radially outward. The stator-side ring magnet 197 is supported by a stator-side support portion 203. The support portion 203 extends through the ring magnet 197 and is suspended by a radial support member 205 of the housing 119. Parallel to the rotation axis 151, the rotor-side ring magnet 195 is fixed by a cover element 207 connected to the support portion 203. The stator-side ring magnet 197 is fixed in one direction parallel to the rotation axis 151 by a fixed ring 209 coupled to the support portion 203 and a fixed ring 211 coupled to the support portion 203. A disc spring 213 may be further provided between the fixed ring 211 and the ring magnet 197.

[0050] An emergency bearing or a safety bearing 215 is provided inside the magnetic bearing. The emergency bearing or the safety bearing 215 idles non - contact during the normal operation of the vacuum pump and only engages when the rotor 149 is displaced excessively radially relative to the stator, thereby forming a radial stopper for the rotor 149 to prevent the collision between the rotor - side structure and the stator - side structure. The safety bearing 215 is configured as a non - lubricated rolling bearing and forms a radial gap together with the rotor 149 and / or the stator. Due to the gap, the safety bearing 215 does not engage during normal pump operation. When the safety bearing 215 engages during radial displacement, and the radial displacement is dimensioned large enough, the safety bearing 215 does not engage during the normal operation of the vacuum pump and is simultaneously small enough to prevent the collision between the rotor - side structure and the stator - side structure in all situations.

[0051] The vacuum pump 111 has an electric motor 125 that rotationally drives the rotor 149. The armature of the electric motor 125 is formed by the rotor 149. The rotor shaft 153 of the rotor 149 extends through the motor stator 217. A permanent magnet assembly may be arranged radially outward or embedded in the portion of the rotor shaft 153 that extends through the motor stator 217. An intermediate chamber 219 is arranged between the motor stator 217 and the portion of the rotor 149 that extends through the motor stator 217. The intermediate chamber 219 has a radial motor gap. Through the motor gap, the motor stator 217 and the permanent magnet assembly may magnetically influence each other to transmit the driving torque.

[0052] The motor stator 217 is fixed within the housing in a motor chamber 137 provided for the electric motor 125. Via a seal gas connection 135, seal gas (also referred to as purge gas, which may be, for example, air or nitrogen) can reach the motor chamber 137. The electric motor 125 can be protected via the seal gas against process gas, for example, against corrosive parts of the process gas. The motor chamber 137 may be evacuated via the pump exhaust port 117. That is, a vacuum pressure realized by an auxiliary vacuum pump connected to the pump exhaust port 117 acts, at least approximately, within the motor chamber 137.

[0053] A so-called labyrinth seal 223, known per se, may be further provided between the rotor hub 161 and the wall part 221 defining the motor chamber 137. Thereby, in particular, a better seal of the motor chamber 217 against the Horvbeck pump stage located radially outside is achieved.

[0054] As already described above, the aforementioned turbo molecular vacuum pump 111 can be vented via a vent valve 133, in which case this vent valve 133 is a simple vent screw screwed into the vent opening of the corresponding housing 119. This vent valve 133 in the form of a simple vent screw can be replaced by the vent valve 10 according to the invention which can be screwed appropriately into the vent opening of the pump housing 119.

[0055] An embodiment of the vent valve 10 according to the invention will now be described below with reference to FIG. 6.

[0056] The ventilation valve 10 shown in a perspective view in Fig. 6 has a valve housing 12 and a valve element 14 accommodated by the valve housing 12. In this case, the valve housing 12 has a male thread 50 on the outer peripheral surface side, and through the male thread 50, the valve housing 12 can be screwed into the ventilation opening of the vacuum pump 111. Further, the valve housing 12 forms a hexagonal contour portion 52, for example, a nut on its outer periphery. In this case, the hexagonal contour portion 52 forms a ring shoulder portion 54 on the side facing the male thread 50. Through the hexagonal contour portion 52, the valve housing 12 can be screwed into the ventilation opening of the vacuum pump 111 using a fork-shaped spanner. Therefore, the ring shoulder portion 54 abuts tightly against the housing 119 with a ring seal (not shown), such as a Usit ring, interposed therebetween.

[0057] The valve housing 12 has a first axial end face 17 adjacent to the hexagonal contour portion 52 and a second axial end face 18 adjacent to the male thread 50. Between the two axial end faces 18 and 20 of both sides, a through hole 16 extends through the valve housing 12, and an internal thread 20 is provided in the through hole 16. The through hole 16 transitions to this at the second axial end face 18 via a conical recess 42.

[0058] Since the valve element 14 accommodated by the valve housing 12 has a male thread 24, the shaft of the valve element 14 may also be referred to as a threaded body portion 22. Since the valve element 14 is screwed into the internal thread 20 of the through opening 16 via the male thread 24, by rotating the valve element 14, the axial position of the valve element 14 with respect to the valve housing 12 can be changed. Preferably, in this case, the two threads 20 and 24 mentioned are formed as left-handed threads, so that the ventilation valve 10 can be opened by rotating the valve element 14 counterclockwise, as generally applied in the case of a closing mechanism.

[0059] To operate the valve element 14, the valve element 14 has, at its first end 25, a rotational drive part in the form of a screw head 28 that is not integrally formed with the screw body 22, adjacent to the first axial end face 17 of the valve housing 12. The screw head 28 is attached to the first end 25 of the screw body 22 only after the screw body 22 is screwed into the through-hole 16 with its first end 25 as the leading end and then screwed through the through-hole 16.

[0060] At the second end 26 opposite to the screw head 28, the screw body 22 has a valve plate 30 integrally formed with the screw body 22, and the valve plate 30 is used to seal the through-hole 16 as required. As can be seen from FIG. 2, the valve plate 30 has a frustoconical portion 44 complementarily formed with respect to the conical recess 32 on the side facing the second axial end face 18. Outside the radial direction of the mentioned frustoconical portion 44, the valve plate 30 has a ring seal 46 on the side facing the second axial end face 18. The ring seal 46 is vulcanized in a steel support ring 47 concentric with the ring seal 46.

[0061] In particular, when the valve element 14 rotates clockwise and is unscrewed from the valve housing 12 until the valve plate 30 abuts against the second axial end face 18 of the valve housing 12 through the ring seal 46 provided in contact with the valve plate 30, the through-hole 16 and thus the vent valve 10 are closed. This position of the valve element is also referred to here as the first axial position of the valve element 14. In this case, the ring seal 46 is pushed into the conical annular gap between the conical recess 42 and the conical portion 44, but at this time, the mechanical overload of the elastomer material constituting the ring seal 46 is prevented by the support ring 47.

[0062] When the valve element 14 is rotated counterclockwise about the first axial position via the screw head 28, the valve element 14 is screwed slightly into the valve housing 12, so that a gap A is formed between the valve plate 30 and the second axial end face 18 of the valve housing 12. This position where the valve plate 30 is separated from the second axial end face 18 by the gap A is also referred to herein as the second axial position of the valve element 14. The second axial position is shown in FIG. 2.

[0063] At the second axial position, since the valve plate 30 does not closely contact the second axial end face 18 of the valve housing 12, based on the thread play already existing between the female thread 20 of the valve hole 16 and the male thread 24 of the screw body 22, air reaches from the atmosphere into the interior of the pump 111 through the through hole 16 or the thread play, whereby the pump 111 is gradually vented.

[0064] However, since the volume flow rate that can be caused by the thread play is limited, according to the present invention, the screw body 22 has an axial channel in the form of a pocket hole 32 along its central axis, and a first radial hole 38 branches from its closed end 36. The first radial hole 38 opens into a ring groove 48 at the second end 36 of the screw body 22. In this case, the depth of the ring groove 48 mentioned is substantially the same as the thread height of the male thread 24 of the screw body 22. Without this ring groove 48, the male thread 24 of the screw body 22 should extend to the valve plate 30, whereby the valve element 14 can be unscrewed until the valve plate 30 contacts the second axial end face 18.

[0065] The first radial hole 38 opens into the gap A between the valve plate 30 and the second axial end face 18 of the valve housing 12 at the second axial position of the valve element 14. Therefore, at the second axial position of the valve element 14, the external atmosphere is granule-connected to the interior of the vacuum pump 11 through the pocket hole 32 and the first radial hole 38 branching from the pocket hole 32. As a result, air can flow into the pump interior from the external atmosphere through the pocket hole 32 and the first radial hole 38, whereby the pump 111 is vented.

[0066] As can be seen particularly from the enlarged detailed view of FIG. 2A, a second radial hole 40 branches off from the pocket hole 32. In this case, the first radial hole 38 is located closer to the valve plate 30 than the second radial hole 40 and has a somewhat smaller hole diameter than the second radial hole 40. The hole diameter of the second radial hole 40 matches the hole diameter of the pocket hole 32.

[0067] In this case, the second radial hole 40 is used to achieve a second ventilation situation. The second ventilation situation is characterized in that ventilation can be performed at a volume flow rate larger than the volume flow rate obtained by the pump 111 through only the first radial hole 38 in this ventilation situation. This is based on the fact that the hole diameter of the second radial hole 40 is larger than the hole diameter of the first radial hole 38. Since the second radial hole 40 is still located within the through hole 16 at the second axial position of the valve element 40 and thus can hardly pass through the flow, in order to enable the pump 111 to be ventilated through the second radial hole 40, it is necessary to further screw the valve element 14 into the valve housing 12. At such a third axial position, when both the first radial hole 38 and the second radial hole 40 open into the space between the valve plate 30 and the second axial end face 18 of the valve housing 12, which is enlarged with respect to the second axial position, at this third axial position, air reaches the inside of the pump 32 from the atmosphere through both the pocket hole 32 and the two radial holes 38, 40. That is, in order to enable the pump 111 to be ventilated as quickly as possible with the air coming from the atmosphere, the valve element 14 can shift to the aforementioned third axial position. This is because at this third axial position, both the radial holes 38, 40 realize a fluid connection between the external atmosphere and the inside of the pump 111.

Explanation of Reference Numerals

[0068] 10 Ventilation valve 12 Valve housing 14 Valve element 16 Through hole 17 First axial end face 18 Second axial end face 20 Female thread 22 Threaded body 24 Male thread 25 The first end of 22 26 The second end of 22 28 Threaded head / rotary drive part 30 Valve plate 32 Pocket hole 34 Open end 36 Closed end 38 First radial hole 40 Second radial hole 42 Conical recess 44 Frustum-shaped part 46 Ring seal 47 Support ring 48 Ring groove 50 Male thread 52 Hexagonal contour part 54 Ring shoulder 111 Turbo molecular pump 113 Intake flange 115 Pump intake 117 Pump exhaust 119 Housing 121 Lower part 123 Electronics housing 125 Electric motor 127 Accessory connection part 129 Data interface 131 Current supply connection part 133 Ventilation intake 135 Seal gas connection part 137 Motor chamber 139 Coolant connection part 141 Bottom surface 143 Screw 145 Bearing cover 147 Fixing hole 148 Coolant pipeline 149 Rotor 151 Axis of rotation 153 Rotor shaft 155 Moving blade 157 Static blade 159 Spacer ring 161 Rotor hub 163 Holbeck rotor sleeve 165 Holbeck rotor sleeve 167 Holbeck stator sleeve 169 Holbeck stator sleeve 171 Holbeck gap 173 Holbeck gap 175 Holbeck gap 179 Connection channel 181 Rolling bearing 183 Permanent magnet type magnetic bearing 185 Splash nut 187 Disk 189 Insert 191 Bearing half on the rotor side 193 Bearing half on the stator side 195 Ring magnet 197 Ring magnet 199 Bearing gap 201 Support part 203 Support part 205 Radial strut 207 Cover element 209 Support ring 211 Fixed ring 213 Disc spring 215 Emergency bearing or safety bearing 217 Motor stator 219 Intermediate chamber 221 Wall part 223 Labyrinth seal A interval

Claims

1. A vent valve (10) for opening and closing a vent opening in a housing (119) of a vacuum pump (111), in particular a turbomolecular vacuum pump (111), a valve housing (12) accommodated in a vent opening of a vacuum pump (111); a valve element (14) contained by said valve housing (12); Equipped with A through hole (16) extends through the valve housing (12) from a first axial end face (17) to a second axial end face (18) of the valve housing (12) and has an internal thread (20). The valve element (14) has a threaded body (22) with an external thread (24) by which the valve element (14) is screwed into the internal thread (20) of the through hole (16). The threaded body (22) has a first end (25) which is connected to the valve element (14) relative to the valve housing (12). a rotary drive (28) for actuating the valve element (14) to vary an axial position of the valve element (14), and a valve plate (30) at a second end (26) opposite the first end (25), the valve plate (30) abutting a second end face (18) of the valve housing (12) to seal the through hole (16) at a first axial position of the valve element (14), the valve plate (30) having a distance (A) from the second end face (18) at a second axial position of the valve element (14).

2. 2. The vent valve of claim 1, wherein the threaded body has an axial channel that provides a fluid connection through the threaded body for venting a vacuum pump only at a second axial position.

3. 3. The vent valve (10) of claim 1 or 2, wherein the axial channel (32) comprises a blind hole (32) having an open end (34) and a closed end (36) formed in the first end (25) of the threaded body (22).

4. 4. The vent valve (10) of claim 3, wherein the threaded shank (22) has at least one radial hole (38, 40) formed therein that is generally radially oriented, the radial hole (38, 40) branching off from the blind hole (32) and exiting the threaded shank (22) at the second end (26).

5. 5. The vent valve (10) of claim 3 or 4, wherein the threaded body (22) is formed with a first radial hole (38) oriented in a generally radial direction and at least one second radial hole (40) oriented in a generally radial direction, the first radial hole (38) being located entirely closer to the valve plate (30) than the second radial hole (40).

6. 6. The vent valve (10) of claim 5, wherein the hole diameter of the second radial holes (40) is greater than the hole diameter of the first radial holes (38), and preferably the hole diameter of the second radial holes (40) is equal to or smaller than the hole diameter of the blind hole (32).

7. 7. The vent valve (10) according to claim 1, wherein the through hole (16) transitions into the second axial end face (18) via a conical recess (42), and the valve plate (30) has, on its side facing the second axial end face (18), a frustoconical portion (44) formed complementarily to the conical recess (42), which is received by the conical recess (42) in a first axial position of the valve element (14).

8. 8. The vent valve (10) according to claim 7, wherein the valve plate (30) supports, on the side facing the second axial end face (18), radially outside the frusto-conical portion (44), a ring seal (46), in particular the ring seal (46) being vulcanized to a steel support ring (47) concentric with respect to the ring seal (46).

9. 9. The vent valve (10) according to any one of claims 1 to 8, wherein the threaded shank (22) has a groove (48) circumferentially adjacent to the valve plate (30) at the second end (25), the groove (48) having a groove depth that corresponds to or is greater than the thread height of the external thread (24) of the threaded shank (22).

10. 10. The vent valve (10) of claim 1, wherein the external thread (24) of the threaded body (22) and the internal thread (20) of the valve housing (12) are formed as left-hand threads.

11. 11. The vent valve (10) according to claim 1, wherein the screw body (22) supports at the first end (25) a screw head attached to the first end (25) of the screw body (22) as a pivot drive.

12. 12. The vent valve (10) according to claim 1, wherein the valve housing (12) has an external thread (24) for screwing the vent valve (10) into a vent opening of a vacuum pump (111), in particular the valve housing (12) has a regular polygonal contour (52), preferably with a hexagonal cross section, between the external thread (24) and the first axial end face (17) of the valve housing (12), forming a radially aligned ring shoulder (54) facing the external thread (24).

13. 13. The vent valve (10) of claim 12, wherein said ring shoulder (54) supports a ring seal, said ring seal being vulcanized to a support ring, in particular made of steel, concentric therewith.

14. 14. The ventilation valve (10) of claim 1, further comprising a locking mechanism that acts / is acting between the valve housing (12) and the valve element (14) when a gap between the valve plate (30) and the second axial end face (18) of the valve housing (12) reaches a predetermined size.

15. A vacuum pump (111), in particular a turbomolecular vacuum pump (111), comprising a housing (119) in which at least one pump stage is present, said housing (119) being formed with a vent opening which leads to the at least one pump stage, said vent opening accommodating the valve housing (12) of the vent valve (10) according to any one of claims 1 to 14.

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