Abstract: Provided is a high-quality electric motor which can be manufactured at a high yield rate. An electric motor comprises a stator which is housed in a motor case, and a rotor which is provided with a shaft and a rotor body section. The shaft is rotatably supported by the motor case, and the rotor body section has a ring magnet disposed inside the stator. A magnet cover into which the rotor body section is inserted has a circular cylinder section which covers the outer peripheral surface of the ring magnet, a turned-back section which is in contact with an end surface of the rotor body section, and a fastening end section which is fastened to a flange section provided to the shaft so as to cover an end surface. An engagement latch section engaging with the rotor is provided to the turned-back section.

Abstract: Disclosed in the present invention are a cooling system, a stator assembly, and an axial magnetic field motor. The cooling system is used for cooling of a stator core, comprises a housing and an enclosed cavity for containing the stator core, and further comprises: a liquid spraying cavity provided on the housing and used for containing liquid; a liquid inlet in communication with the liquid spraying cavity; a liquid outlet in communication with the enclosed cavity; and a liquid spraying assembly provided on an inner wall, corresponding to the stator core, of the housing.

Abstract: A blower includes a housing including an inlet and an outlet, a bearing-housing structure provided to the housing and adapted to rotatably support a rotor, a motor provided to the bearing-housing structure and adapted to drive the rotor, and an impeller provided to the rotor. The bearing-housing structure includes a bearing shaft having a bearing surface that rotatably supports the rotor. The bearing shaft provides only a single bearing of the non-ball bearing type for the rotor.

Abstract: The disclosure relates to a high-speed radial fan and to a rotor assembly (10) for a high-speed radial fan, comprising a bearing tube (20) which is axially open in the interior and in which a shaft (40) carrying a fan wheel (30) is mounted with a rotor (50), wherein the rotor (50) of the rotor assembly (10) is mounted in a cylindrical separating can (3).

Abstract: An electrical machine for a vehicle may include a rotor, a stator, a coolant distributor chamber and a coolant collector chamber. The rotor may be configured to be rotated about an axis of rotation defining an axial direction of the electrical machine. The stator may include a plurality of stator windings. The coolant collector chamber may be axially arranged at a distance from the coolant distributor chamber. The coolant distributor chamber may be configured to communicate fluidically with the coolant collector chamber by at least one cooling channel through which a coolant can flow. At least one of the stator windings may be embedded in at least one plastic mass consisting of an electrically insulating plastic for thermal coupling to the coolant. At least one of the coolant distributor chamber and the coolant collector chamber may be arranged at least partially in the at least one plastic mass.

Abstract: An electric submersible pump (ESP) assembly. The ESP assembly comprises a centrifugal pump, an electric motor mechanically coupled by a drive shaft to the centrifugal pump, wherein the electric motor comprises a stator and a rotor, a bearing, wherein the bearing is disposed inside the electric motor, and a magnetic shield disposed in the electric motor between bearing and the rotor and stator.

Abstract: A drive train (1) for a motor vehicle (100) has an electric machine (2) with a rotor (3), a stator (4) and an air gap (5) between the rotor (3) and the stator (4). The drive train (1) also has a transmission (6) and a cooling circuit (7) for conducting a coolant through the electric machine (2) and the transmission (6). The coolant is provided for lubricating and cooling the transmission (6) and for directly cooling electrical conductors of the stator (4). The cooling circuit (7) is provided in such a way that the coolant does not enter the air gap (5).

Abstract: The invention can include a device and method for distributing a fluid in an industrial facility that comprises a fluid distribution pipe, a discharge pipe, a distribution valve that is positioned on the distribution pipe and controlling the distribution of fluid between an upstream area and a downstream area, a discharge valve positioned on the discharge pipe, and measuring means for measuring, in real time, a characteristic parameter of the distribution of the fluid within one of the pipes. A module is also included for calculating a sliding threshold value of the characteristic parameter and means configured to control the partial gradual opening or closing of the discharge valve depending on the result of the comparison of said sliding threshold value with an instantaneous value of the characteristic parameter, in order to improve reliability of the industrial facility.

Abstract: A permanent magnet motor and a compressor are provided. The motor has a rotor, a stator core, and a stator winding. A plurality of coupled coils are disposed on the stator core. The coil includes a first type coil and a second type coil. The stator winding is a three-phase stator winding. Each phase of the stator winding is provided with three joints In each phase, a first joint and a second joint are disposed on the first type coil, a third joint in the stator winding of each phase is disposed on the second type coil. The permanent magnet motor provided by the present disclosure can improve the efficiency of the motor and reduce noise.

Abstract: A motor may include a rotor provided with a rotating shaft that protrudes to a first side in an axial direction; a stator disposed on an outer peripheral side of the rotor; a resin sealing member that covers the stator; and a cover member that is disposed on the first side of the resin sealing member and supports the rotating shaft. The cover member may include a plurality of gate marks disposed at different angular positions and a plurality of ribs that protrude to a second side in the axial direction. The ribs may be disposed at positions where each midpoint between the gate marks adjacent to each other in the circumferential direction overlap with an axis of the rotor.

Abstract: A motor includes a shaft, a bearing supporting the shaft, an armature disposed radially outward of the bearing, a bracket to which the bearing and the armature are fixed, and a rotor connected to the shaft. The bracket includes a bracket bottom portion covering a lower side of the armature, and a terminal holding portion extending radially outward from an outer peripheral portion of the bracket bottom portion. The terminal holding portion includes a plate-shaped holding portion main body connected to the outer peripheral portion of the bracket bottom portion, a terminal disposed on an upper surface of the holding portion main body, and a protrusion portion projecting downward from a lower surface of the holding portion main body at a same position in a radial direction as that of the terminal, or radially outward of the terminal.

Abstract: An electric motor, especially for a fluid-handling system, comprises an external stator and an internal rotor mounted to rotate around an axis. The said external stator comprises a multiplicity of ferromagnetic pole pieces disposed around the axis and having winding cores extending substantially radially, an injection-molded plastic structure having a bushing and, molded thereon, winding supports enveloping the winding cores, as well as stator windings received on the winding supports. The bushing comprises a sleeve having a closed inner face extending radially inside the pole pieces and an end piece that closes the sleeve in the end region. The rotor is disposed inside the sleeve and mounted in a bearing disposed in the end piece.

Abstract: Provided are: a motor for which high strength can be obtained in a motor casing; and a compressor that uses the motor. This motor 10 has: a rotating shaft 12 provided in a rotatable manner; a rotor 32 that rotates integrally with the rotating shaft 12; a stator 31 that rotationally drives the rotor 32; and a motor casing 14 that is a cylindrical body for accommodating the rotor 32 and the stator 31, and has, on the outer circumferential surface thereof, ribs 22 extending in a circumferential direction.

Abstract: The purpose of the present invention is to facilitate evaluating the precision of a pipe network model without using flow information. An analysis device according to an embodiment of the present invention comprises a transfer characteristic derivation unit which derives a transfer characteristic which represents a relation between a voltage in a plurality of nodes which are included in an electrical circuit which is a model of a pipe network through which a fluid flows and a voltage in an interior node which is a different node of the electrical circuit from the plurality of nodes, and a computation unit which, on the basis of the transfer characteristic and the pressure of the fluid at positions within the pipe network which correspond to the plurality of nodes, computes the pressure of the fluid at a position within the pipe network which corresponds to the interior node.

Abstract: A fluid pump includes a fluid pump inlet and a fluid pump outlet. A motor includes an armature and a stator such that the armature rotates about an axis. A pump section includes a pump section having a pumping element coupled to the armature such that rotation of the armature rotates the pumping element such that the pumping element pumps fluid from the fluid inlet to a pump section outlet of the pump section. A fluid passage within the fluid pump provides fluid communication from the pump section outlet to the fluid pump outlet such that the armature in part defines the fluid passage. The armature includes blades arranged in a polar array centered about the axis such that each of the blades extends in a helix about the axis and such that the blades define chambers. The chambers are in constant fluid communication with the pump section outlet.

Abstract: Certain aspects of the subject matter described here can be implemented in a downhole-type electric submersible pump system. An electric machine can be disposed downhole in a wellbore. The electric machine is coupled to rotate with an impeller that can be disposed downhole in the wellbore. The electric machine includes a stator assembly with at least three stator sections axially arranged and spaced apart from each other along a longitudinal axis of the electric machine. The electric machine also includes a rotor assembly with at least three rotor sections arranged axially along the longitudinal axis of the electric machine. The rotor assembly is carried within and supported to rotate by the stator assembly.

Abstract: A motor includes a stationary portion and a rotary portion. The stationary portion includes an armature, a circuit board below the armature, and a base portion. The base portion includes a bearing holder and a radial gap is defined between the circuit board and a wall portion. The circuit board includes a through-hole passing through the circuit board, and at least one exhaust hole passing through the circuit board in an axial direction. A filler material is on upper and lower sides of the circuit board. The radial gap, a first exhaust hole extending in a radial direction, and a second exhaust hole extending in a circumferential direction from the first exhaust hole communicate with each other through an axial space between a lower surface and an upper surface of the base portion.

Abstract: An electrically driven pump includes a rotor assembly, and the rotor assembly includes a first part and a second part. The first part is integrally formed by injection molding, and includes an upper plate and vanes of an impeller, the upper plate is integrally formed with the vanes by injection molding, and each of the vanes is formed with a first connecting portion. The second part is integrally formed by injection molding, the first part and the second part are fixed by welding the first connecting portion and a second connecting portion, and in this way, the manufacturing cost of the rotor assembly is reduced, also a shaft sleeve integrally formed has a simple forming process.

Abstract: A pump having a canned motor which has a stator with an internal rotor disposed therein, the stator and the internal rotor being mutually separated fluid-tightly by a can disposed between stator and internal rotor, the stator having stator teeth which extend radially in the direction of the internal rotor and define with appurtenant stator-tooth end faces a receiving space for the internal rotor and the can, the can lying against the stator-tooth end faces, the can having on its surface facing the stator, in stator-tooth gaps which are respectively defined by two mutually adjacent stator teeth, ribs fitted in in a form-locking manner which taper in the radial direction, starting out from a rib root disposed on the can, with regard to a rib thickness defined in the circumferential direction of the can.

Abstract: An electric pump is provided according to the application, which includes a housing, a shaft, an impeller, a rotor assembly, a stator assembly and an inner chamber. The shaft, the impeller and a rotor are arranged in the inner chamber. The housing includes a first housing, a partition and a second housing, and the partition divides the inner chamber into a wet chamber and at least one dry chamber. The partition includes a first side wall, a first bottom, a second side wall and a second bottom. The second side wall isolates the rotor assembly and the stator assembly. An outer peripheral surface of the second side wall is provided with reinforcing ribs, and the reinforcing ribs improve the strength of the second side wall.

Abstract: Provided is a canned motor to be coupled to a vacuum pump and used as a rotary driving source for the vacuum pump. The canned motor includes: a stator core; a rotor provided on an inner side of the stator core; and a non-conductive can provided between the stator core and the rotor. The non-conductive can is configured to separate the stator core and the rotor from each other. The non-conductive can is made of resin, ceramic, or composite material thereof. The non-conductive can is bonded to the stator core with an adhesive.

Abstract: Provided is an electric motor capable of stabilizing a preload applied to a bearing by an annular spring and effectively retarding degradation of the annular spring. The electric motor includes a motor shaft, a rotor, a stator, a housing containing the rotor and the stator in a posture where the motor shaft extends vertically, an upper bearing and a lower bearing supporting the motor shaft, and an annular spring applying a downward preload to the upper bearing. The lower bearing is fixed to the motor shaft and the housing. The housing has a load-receiving surface receiving an upward thrust load overcoming the preload from the upper bearing.

Abstract: A wet-running centrifugal pump includes an electric motor (1) and a centrifugal pump (7) which is driven thereby. The electric motor (1) has a rotor (4) which is rotatably arranged within the stator (3). A canned pot (13), which carries a motor-side bearing for the rotor (4), is provided between the rotor and the stator. Moreover, a bearing plate (19) is provided, which carries a pump-side bearing for the rotor (4), wherein the bearing plate (19) is fixed on the housing side, and in the region of the pump-side bearing immerses into the canned pot. A radial seal (20) is provided between the bearing plate (19) and the canned pot (13).

Abstract: The invention relates to a pump. The pump has a pump housing comprising a first and second housing part (1, 2). The first housing part (1) has a first fluid port (10) and a first face side (8). The second housing part (2) has a second fluid port (27) and a second face side (9). The second housing part is axially connectable with the first housing part (1). Further, the pump has a pump motor in the first housing part (1) and a fluid mover in the second housing part (2). The fluid mover is drivable by the pump motor. Further, the pump has a housing part connecting device (3) for axially connecting the first housing part (1) and the second housing part (2) with each other. The housing part connecting device (3) is adjustable between a connecting and a release position. In the connecting position, the first housing part (1) and the second housing part (2) are fixed in an axial and rotary manner with each other.

Abstract: There is provided a method of manufacturing a laminated rotor core, including: a mounting step of placing a core body on a carrier tray, the core body having a plurality of magnet insertion holes provided around the shaft hole, the carrier tray having a mount plate and a columnar guide member standing on a front surface of the mount plate 41, the placement of the core body being carried out by fitting the guide member into the shaft hole; an inserting step of inserting permanent magnets respectively in the magnet insertion holes; an injecting step of injecting a liquefied resin material in each of the magnet insertion holes; and a first preheating step of heating the core body before the mounting step, wherein the inserting step and the injecting step are carried out in a state in which the core body is placed on the carrier tray.

Abstract: Provided is a canned motor to be coupled to a vacuum pump and used as a rotary driving source for the vacuum pump. The canned motor includes: a stator core; a rotor provided on an inner side of the stator core; and a non-conductive can provided between the stator core and the rotor. The non-conductive can is configured to separate the stator core and the rotor from each other. The non-conductive can is made of resin, ceramic, or composite material thereof. The non-conductive can is bonded to the stator core with an adhesive.

Abstract: A canned motor pump is provided that includes a rotor of a motor and a shaft shaped as a bar. The shaft penetrates through and is coupled with the rotor. A bearing is shaped as a circular cylinder, and is coupled to an upper side of the rotor. Further, the shaft penetrates through the bearing. A housing surrounds the rotor and the bearing to expose an upper end of the bearing and to house the rotor and the bearing within the housing.

Abstract: Provided is a canned motor to be coupled to a vacuum pump and used as a rotary driving source for the vacuum pump. The canned motor includes: a stator core; a rotor provided on an inner side of the stator core; and a non-conductive can provided between the stator core and the rotor. The non-conductive can is configured to separate the stator core and the rotor from each other. The non-conductive can is made of resin, ceramic, or composite material thereof. The non-conductive can is bonded to the stator core with an adhesive.

Abstract: A flow-conditioning system includes a pump, process tubing coupling the pump to a source of multiple component process fluid, and an in-line flow-mixing device positioned in the process tubing upstream of the pump. A system includes a well disposed below a body of water and providing a source of multiple component fluid, a pump disposed in and exposed to the water, process tubing coupling the pump to the well, and an in-line flow-mixing device positioned in the process tubing upstream of the pump.

Abstract: A motor waterproof structure includes a stator assembly, a casing and a cover body. The casing has a receiving space formed with an open side. A circuit board is disposed in the receiving space. The cover body is disposed on the open side of the receiving space to cover the circuit board. The motor waterproof structure serves to effectively protect the circuit board from being short-circuited and burned out in a humid environment.

Abstract: A canned motor pump includes a stator assembly and a housing surrounding the outer portion of the state assembly. The housing is coupled with the stator assembly in a state in which the housing is divided into a plurality of pieces by cutting lines, and has a through-hole in a side portion into which a fastener is fastened. A fixing ring is coupled to the inside of the housing and the stator assembly so as to provide a seal between the housing and the stator assembly.

Abstract: A rotating electrical machine according to the present invention includes a can formed in a tubular shape and made of fiber reinforced plastic. At least a part of a first end portion of the can is located on a radially outer side of an adhered portion of a first end member, and a resin-based adhesive is filled in a gap between the part of the first end portion and the adhered portion of the first end member. At least a part of a second end portion of the can is located on a radially outer side of an adhered portion of a second end member, and the resin-based adhesive is filled in a gap between the part of the second end portion and the adhered portion of the second end member.

Abstract: In accordance with one embodiment, a machine for generating electrical energy comprises a housing. A rotor has interior blades for rotation in response to receipt of material. The rotor has an outer surface and an inlet. A first magnet assembly is secured to the outer surface of the rotor. A first stator winding is in electromagnetic communication with the corresponding first magnetic assembly, such that if the rotor rotates a first electromagnetic signal energizes the first stator windings based on the flow of material into or through the inlet.

Abstract: A transport apparatus including a housing, a drive mounted to the housing, and at least one transport arm connected to the drive where the drive includes at least one rotor having at least one salient pole of magnetic permeable material and disposed in an isolated environment, at least one stator having at least one salient pole with corresponding coil units and disposed outside the isolated environment, where the at least one salient pole of the at least one stator and the at least one salient pole of the rotor form a closed magnetic flux circuit between the at least one rotor and the at least one stator, and at least one seal configured to isolate the isolated environment where the at least one seal is integral to the at least one stator.

Abstract: A jacketed electromagnetic machine stator for a pressurized rotary machine operating in a corrosive atmosphere containing H2S or wet CO2 and including a plurality of pole pieces separated from a rotor by an airgap, wherein the hermetically sealed enclosure protecting said stator from said corrosive atmosphere includes a jacket constituted by a non-magnetic cylinder having magnetic material inlays situated in register with said pole pieces and that are not in contact with said corrosive atmosphere, said hermetically sealed enclosure being constituted externally solely by parts made of non-magnetic material that are secured to one another by welds that have not been subjected to any heat treatment.

Abstract: In a jacketed active magnetic bearing for a rotary machine having a rotor in contact with a process gas, there is provided a magnetic bearing comprising a bearing armature of laminated magnetic material secured to said rotor, a bearing stator protected by a first jacket of magnetic anti-corrosion material that co-operates with first housing portions to form a first leaktight housing enclosing the bearing stator, the first jacket being made of a ferritic stainless steel, and the first housing portions having insert parts that are also made of ferritic stainless steel, and that are connected by welds to a housing end-wall portion made of a magnetic anti-corrosion material, the laminated magnetic material forming the bearing armature and the detector armature also being a ferritic stainless steel.

Abstract: A pump having a canned motor which has a stator with an internal rotor disposed therein, the stator and the internal rotor being mutually separated fluid-tightly by a can disposed between stator and internal rotor, the stator having stator teeth which extend radially in the direction of the internal rotor and define with appurtenant stator-tooth end faces a receiving space for the internal rotor and the can, the can lying against the stator-tooth end faces, the can having on its surface facing the stator, in stator-tooth gaps which are respectively defined by two mutually adjacent stator teeth, ribs fitted in in a form-locking manner which taper in the radial direction, starting out from a rib root disposed on the can, with regard to a rib thickness defined in the circumferential direction of the can.

Abstract: A motor includes a cover made of a resin material. The cover includes a first annular portion arranged to extend in an annular shape above coils, a side wall portion arranged to extend downward from an outer circumferential portion of the first annular portion, and a second annular portion arranged to extend radially outward or radially inward from a lower end portion of the side wall portion along an upper surface of a circuit board. The side wall portion is arranged to extend in an axial direction while filling in gaps between teeth on a radially inner side of radially outer end surfaces of the teeth. The coils are covered by the cover to be protected from dust, water droplets, etc. The radially outer end surfaces of the teeth are exposed from the cover, and are thus arranged to be in radial proximity to a rotor magnet.

Abstract: A turbomachine includes a motor including a rotor assembly and a stator assembly. A sleeve fluidly separates the rotor assembly from the stator assembly. The sleeve has first and second ends axially spaced from one another. In one example, first and second seals are arranged at the first end and fluidly separate the rotor assembly from the stator assembly. The second seal is arranged downstream from the first seal relative to the rotor assembly. In another example, the sleeve includes wet and dry sides. A first seal is arranged at the first end on the wet side. A drain is provided in the housing and arranged in a region downstream from the first seal. The drain fluidly connects the region to an exterior of the housing.

Abstract: A vacuum actuator includes a vacuum partition wall, the interior of which can be evacuated to a vacuum, a rotor supported by the vacuum partition wall to be free to rotate, a permanent magnet provided on the outer peripheral surface of the rotor, a coil opposed to the permanent magnet, and a stator provided with the coil. The stator and the vacuum partition wall are formed integrally with each other.

Abstract: A rotor for an electric motor includes a metal core, a plurality of electrical conductors arranged on the metal core, and a metallic corrosion protection layer enveloping the metal core and the plurality of conductors. The corrosion protection layer is laid as a solid body around the metal core and the conductors and fastened at least to the metal core. The corrosion protection layer is at least a part of a hot-pressing containment for isostatic pressing of the conductors in the metal core.

Abstract: A rotor for an electric motor is provided. The rotor includes a metal cone upon which a plurality of electrical conductors are arranged. A metallic corrosion protection layer is provided that envelopes the metal core and the conductors. The corrosion protection layer is laid around the metal core and the conductors as a solid body and fastened at least to the metal core. The corrosion protection layer is at least a part of a hot-pressing containment for isostatic pressing of the conductors in the metal core. The rotor, which is suitable for a high-speed electric motor for the industrial sector, can be produced at low cost and can be used reliably to compress chemically aggressive industrial process gases.

Abstract: Motor modules for multi-arm robot apparatus are described. The motor modules can be used individually or stacked and assembled to make up one-axis, 2-axis, 3-axis, 4-axis, 5-axis, 6-axis motor assemblies, or more. One or more of the motor modules have a stator assembly including a stator received in the stator housing, and a rotor assembly abutting the stator assembly, the rotor assembly including a rotor housing, a drive shaft, a bearing assembly supporting the drive shaft, and a rotor coupled to the drive shaft. A vacuum barrier member is positioned between the rotor and the stator. Multi-axis motor drive assemblies, multi-axis robot apparatus, electronic device manufacturing systems, and methods of assembling drive assemblies are described, as are numerous other aspects.

Abstract: A dynamoelectric machine, such as a totally enclosed fan cooled (TEFC) induction motor has a double-wall bearing housing heat shield that envelops and thermally isolates the bearing housing from the rest of the motor housing interior. The shield defines an air channel between the shield outer and inner walls. Optionally the air channel may be constructed to enable circulating air flow through a shield intake in communication with an air flow source, such as air ducted from the TEFC motor axial cooling fan. The air channel also defines an exhaust. Air flow within the air channel transfers heat out of the motor housing, lowering bearing housing operating temperature. Air flow rate may be varied in response to motor operational parameters.

Abstract: An electric machine, in particular an electric motor, has a one-piece can disposed between a stator and a rotor. The can has a tubular casing, which is loaded with external pressure by a coolant in a machine housing and which is made of fiber composite material. The casing thickness of the can lies between 2.5 mm and 0.5 mm. The can is axially fitted onto a sleeve and the sleeve is mounted to a collar of an end plate of the machine housing. The sleeve has a first axial section projecting into the can and a second axial section aligned with the can.

Abstract: A canned motor pump, wherein a motor stator is housed in a stator chamber that is a space between a tubular stator can for housing a motor rotor and a tubular stator band disposed coaxially with the stator can. The stator chamber is closed by annular end plates at the cylindrical ends between the stator can and the stator band. The stator chamber is filled with a filler. The filler is produced from spherical inorganic material particles filled into the stator chamber and resin for causing the particles to stick to each other. Consequently, the heat release performance of the stator of the canned motor pump is improved.

Abstract: A pump unit includes a motor, a pump, a shaft spanning the motor and the pump, and at least a first magnetic bearing supporting the shaft. A hydrocarbon production system includes an underwater well and a pump unit exposed to an underwater environment. The pump unit is operable to pump a production fluid from the well and includes a motor, a pump, a shaft spanning the motor and the pump, and at least a first magnetic bearing supporting the shaft.

Abstract: A thermal shield for a system for generating electric power may include a sheet of material configured to be operably associated with an engine of the system for generating electric power such that heat from the engine is deflected back toward the engine. The sheet of material may define a generally rectangular shape defining a length dimension and a width dimension, and the length dimension may be configured to generally correspond to a length defined by the engine.

Abstract: A motor stator assembly includes an iron core, a coil unit and a dustproof ring. The coil unit is coupled with the iron core. The iron core is spaced from a predetermined part of the coil unit by a gap when coupled with the coil unit. The dustproof ring is fitted around the predetermined part of the coil unit to cover the gap between the iron core and the predetermined part of the coil unit.

Abstract: An electric motor or generator having a stator with stator teeth for mounting electrical coils and a rotor, wherein the stator has a first surface that is parallel to an axis of rotation of the rotor and is axially separated from the stator teeth and the rotor has a second surface that is formed in substantially the same axial position as the stator s first surface, wherein material is mounted on the first surface or the second surface that has a lower frictional coefficient than the first surface or second surface.