A semi-rigid stator is provided for a helical gear device. The stator includes a stack of rigid rings, a deformable layer, and a rigid housing. Each of the rigid rings has a central opening and an exterior surface. The rigid rings are aligned along a common centerline and rotated slightly relative to each other such that the stack of rigid rings forms a helically convoluted chamber. Each of the rigid rings is secured within the rigid stator housing by the deformable layer disposed between the exterior surface of each of the rigid rings and the rigid housing. The deformable layer bonds the rigid rings together as the ring stack and permits movement of the rigid rings relative to each other.

A module for a vacuum pumping and/or abatement system includes a top side, a bottom side, a front side, a rear side, and two opposing lateral sides, which together define a space. The module comprises an apparatus located wholly within the space and one or more connection points coupled to the apparatus. Each of the connection points is for receiving an input for the apparatus or receiving an output from the apparatus. The one or more connection points are located at the top side. The module has a maximum size in a first system dimension that is equal to a first integer multiple of a fixed system value, the first system dimension being a dimension between the lateral sides. For each connection point, a distance between that connection point and each lateral side in the first system dimension is a respective second integer multiple of the fixed system value.

A vacuum system pipe coupling includes a first coupling member defining a through passage, a second coupling member defining a through passage and a securing unit. The first coupling member has a first end portion having a first lengthways extending axis, a second end portion having a second lengthways extending axis that is laterally offset with respect to the first lengthways extending axis and a first connecting portion connecting the first and second end portions. The second coupling member has a third end portion having a third lengthways extending axis, a fourth end portion having a fourth lengthways extending axis that is laterally offset with respect to the third lengthways extending axis and a second connecting portion connecting the third and fourth end portions. The securing unit is configured to secure the first end portion to the third end portion with the first and third lengthways extending axes in alignment.

A vacuum pumping and/or abatement system for evacuating and/or abating fluid from an entity, the system comprising: a first module comprising a vacuum pumping apparatus for pumping the fluid from the entity and/or an abatement apparatus for abating the fluid evacuated from the entity; and a second module arranged adjacent to the first module in a first system dimension; wherein the first and second modules each have a maximum size in the first system dimension that is a respective integer multiple of a common fixed system value.

A multi-stage dry Roots vacuum pump, including a pump body, multi-stage Roots working units and a plurality of drive components. The pump body is provided with a plurality of independent working chambers, and airflow channels communicating the various working chambers; the airflow channels are communicated with outside; the Roots working units of each stage include driving Roots rotors and driven Roots rotors; the driving Roots rotors and driven Roots rotors are positioned in the working chambers; and the various drive components are respectively used for driving the driving Roots rotors and driven Roots rotors positioned in the various working chambers to rotate towards opposite directions at the same rotating speed. The Roots working units of various stages may be randomly distributed at various positions of the pump body on premise of ensuring that the airflow channels can communicate the working chambers of each stage.

A stator for a progressive cavity pump may include a containment element with an inner surface and a casing. The casing may be arranged within the containment element, be generally isolated from the inner surface of the containment element, and define a stator cavity adapted for receiving a progressive cavity pump rotor and for accommodating substantially free rotation of the progressive cavity pump rotor therein.

A stator segment is provided for a helical gear device. The stator segment includes a stator tube and modular stator inserts. The stator tube has an inner profile with at least two internal sides that extend longitudinally along an interior of the stator tube. The modular stator inserts each have an outer profile that substantially matches and fits within the inner profile of the stator tube. The modular stator inserts also each have an interior helical profile that defines a central opening. The modular stator inserts are configured to be removably inserted longitudinally into the stator tube along the inner profile of the stator tube. The inner profile aligns the modular stator inserts to form a continuous helical chamber and prevents rotation of the modular stator inserts relative to the stator tube.

Disclosed herein is a scroll compressor that includes a first bearing rotatably supporting a rotary shaft relative to a casing at one side of the rotary shaft with respect to a motor, a second bearing rotatably supporting the rotary shaft relative to the casing at the other side of the rotary shaft with respect to the motor, and a third bearing rotatably supporting the rotary shaft relative to an orbiting scroll at the opposite side of the first bearing with respect to the second bearing, wherein the distance between a first bearing center and a third bearing center may be a predetermined distance, the distance between a motor center and the third bearing center may be longer than the distance between the motor center and the first bearing center, and the distance between a second bearing center and the motor center may be longer than the distance between the second bearing center and the third bearing center. Thus, it is possible to prevent the damage of the second bearing under poor load conditions.

In a rotor in rotor configuration, a pump has inward projections on an outer rotor and outward projections on an inner rotor. The outer rotor is driven and the projections mesh to create variable volume chambers. The outer rotor may be driven in both directions. In each direction, the driving part (first inward projection) of the outer rotor contacts a sealing surface on one side of an outward projection of the inner rotor, while a gap is left between a sealing surface of the other side of the outward projection and a second inward projection. The gap may have uniform width along its length in the radial direction, while in a direction parallel to the rotor axis it may be discontinuous or have variable size to create flow paths for gases.

A multistage pump assembly with at least one co-used shaft comprises a first pump set including at least two vacuum chambers. Each vacuum chamber of the first pump set is installed with at least one rotor and a first driving shaft, the rotor is installed to the first driving shaft in the same vacuum chamber of the first pump set. The first driving shafts in the first pump set are co-shafted, that is, rotors in the at least two vacuum chambers of the first pump set are installed at the same first driving shaft. A second pump set includes at least one vacuum chamber which includes at least one rotor and a second driving shaft. An outlet of the second pump set is connected to an inlet of the first pump set through an air tube.