Lubricant Metering Structure Patents (Class 384/399)
  • Patent number: 8721183
    Abstract: A bearing assembly is formed by coupling at least two units together in an axially abutting manner. Each unit has two connection portions on two opposite ends and a mounting portion on a largest outer periphery. The connection portions between two adjacent units form at least one set of interfaces, each set having complementary shapes contact with each other. The mounting portion is securely encased in an inner periphery of a jutting chamber located at each end of a motor housing. At least one groove and notches are formed on at least one of two abutting connection portions between the two adjacent units. The notches communicate with the groove and an axle hole. In the assembly, the groove forms at least one storage chamber to store lubricating media, and the notches form at least one set of passages communicating with the storage chamber and an axial hole.
    Type: Grant
    Filed: January 4, 2013
    Date of Patent: May 13, 2014
    Assignee: Newcera Technology Co., Ltd.
    Inventors: Lung-Wei Huang, Chao-Nien Tung
  • Patent number: 8567067
    Abstract: A method of manufacturing a bearing mechanism of a motor includes steps a)-e). In step a), a bearing assembly is assembled. In step b), an upper seal gap between an upper thrust portion and an upper hub annular portion is arranged to face downward to increase the width of a gap between an outer tubular portion and a flange portion, or a lower seal gap between the outer tubular portion and a lower hub annular portion is arranged to face downward to increase the width of a gap between the upper thrust portion and the flange portion. In step c), pressure in all gaps is reduced. In step d), lubricating oil is injected into the upper or lower seal gap which faces upward, and a predetermined time or longer is allowed to pass. In step e), pressure is returned to atmospheric pressure.
    Type: Grant
    Filed: January 19, 2012
    Date of Patent: October 29, 2013
    Assignee: Nidec Corporation
    Inventors: Katsuki Yamaguchi, Shigeki Horiki, Yoshitsugu Hideshima, Akio Tatsumi, Akinobu Sumiji, Takehito Tamaoka, Kazushi Miura, Mitsuhiro Takemoto
  • Publication number: 20130181557
    Abstract: There are provided a fluid injecting method capable of easily injecting oil into a motor and an apparatus for implementing the same, and a motor manufactured using the same. The fluid injecting method includes: connecting a shaft and a sleeve to each other to thereby assemble a bearing assembly; disposing at least one bearing assembly under a dispenser in a state in which the bearing assembly is tilted at a predetermined angle; and injecting a fluid into the bearing assembly.
    Type: Application
    Filed: April 5, 2012
    Publication date: July 18, 2013
    Inventor: Seung Dong KIM
  • Patent number: 8113716
    Abstract: A bearing (crank bearing 6) is constituted of an upper bearing (61) that is attached to a cylinder block, a lower bearing (67) that is attached to a crank cap, and a bearing filter (71) for filtering engine oil. The bearing filter (71) is fitted in an oil hole (62A) of the upper bearing (61).
    Type: Grant
    Filed: June 29, 2007
    Date of Patent: February 14, 2012
    Assignee: Toyota Jidosha Kabushiki Kaisha
    Inventors: Takashi Kikuchi, Yutaka Matsuyama
  • Patent number: 7802656
    Abstract: An improved wick-holder for mounting a felt lubricating wick is provided with a passive inertia-activated pump mounted for submersion in the axle-cap lubricant-reservoir at a level that ensures that for all levels of the reservoir, the pump inlet is submerged in the lubricant of the reservoir. In a first embodiment, the passive inertia-activated pump takes the form of a piston-type pump, while in a second embodiment, the passive inertia-activated pump takes the form of a diaphragm pump. In either embodiment, the inlet of the passive inertia-activated pump is submersed in the lubricant-reservoir, and the output of the passive inertia-activated pump is directed to the surface-interface between the felt wick and the axle journal surface-area to increase the lubrication thereof over and above that which normally ensues owing to the conventional capillary action of the felt wick.
    Type: Grant
    Filed: January 20, 2006
    Date of Patent: September 28, 2010
    Assignee: Magnus Division of LV Ventures, Inc.
    Inventors: John E. Macklin, Robert B. Foster, Paul Bien
  • Patent number: 7611287
    Abstract: A slide bearing for supporting a shaft and comprising at least one bearing shell for receiving the shaft. The bearing shell and the surface of the shaft define a bearing gap. Also described is a mechanism for supplying a lubricant to the bearing gap so that the lubricant can be removed therefrom. To compensate for negative effects of a temperature-dependent change of the bearing gap, there is provided at least one throttling element for throttling the flow of lubricant through the bearing gap.
    Type: Grant
    Filed: May 10, 2006
    Date of Patent: November 3, 2009
    Assignee: Carl Freudenberg KG
    Inventors: Eberhard Bock, Martin Gramlich
  • Patent number: 7413054
    Abstract: A bearing lubrication (oil circulation) system having a check valve configuration for preventing overflow of an oil reservoir or tank. The pressurized oil circulation system may comprise a pump that pressurizes oil from the tank and circulates the oil through a supply conduit to a bearing, and returns the oil to the tank through a return conduit. The system may include a check valve disposed in the supply conduit and a pilot-operated check valve disposed in the return conduit. The pilot may be taken from the supply conduit upstream of the check valve disposed on the supply conduit. When pressure is discharged from the oil circulation, such as with shutdown of a circulation pump, the check valves automatically close and thus prevent oil contained in the supply and return conduits from draining (i.e., by gravity) to the oil tank. Therefore, flooding of the oil tank with excessive oil is prevented. Furthermore, loss of oil from the bearing sump is also prevented.
    Type: Grant
    Filed: August 3, 2004
    Date of Patent: August 19, 2008
    Assignee: Reliance Electric Technologies, LLC
    Inventor: Yehia El-Ibiary
  • Patent number: 7073630
    Abstract: A fluid injection apparatus for a bearing includes a bearing support surface for supporting the bearing so that a seal space is defined between the support surface and the bearing, a fluid injection passage comprised of an oil tank, a first conduit connecting the oil tank to the seal space, and an injection valve provided in the conduit, a decompression passage comprised of an oil recovery tank, a second conduit connecting the oil recovery tank to the seal space, a vacuum pump connected to the seal space through the oil recovery tank, and a decompression valve provided in the second conduit, and a sequence control unit for evacuating the bearing by closing the injection valve, opening the decompression valve, and turning on the vacuum pump, and then filling the bearing with lubricating oil by turning off the vacuum pump, closing the decompression valve, and opening the injection valve.
    Type: Grant
    Filed: April 9, 2003
    Date of Patent: July 11, 2006
    Assignee: Seiko Instruments Inc.
    Inventors: Mitsuharu Iwamoto, Tetsuya Nagata
  • Patent number: 6976559
    Abstract: The invention relates to a piston compressor, particularly a hermetically enclosed refrigerant compressor, with a crank drive, having a crank shaft with an eccentric crank pin and an oil channel arrangement, and a connecting rod with a first piston-side connecting rod eye and a second pin-side connecting rod eye, said eyes having between them a connecting rod shank with a longitudinal channel, which opens into the connecting rod eyes. In this compressor, it is endeavoured to improve the lubricating conditions. For this purpose a bearing element is arranged between the crank pin and the second connecting rod eye, which is unrotatably connected with the second connecting rod eye under formation of an oil channel, the longitudinal channel communicating with the oil channel and a control arrangement being provided, which ensures a communication between the oil channel and the oil channel arrangement at least once per rotation of the crank pin.
    Type: Grant
    Filed: October 15, 2001
    Date of Patent: December 20, 2005
    Assignee: Danfoss Compressors GmbH
    Inventors: Frank Holm Iversen, Preben Bjerre
  • Patent number: 6425689
    Abstract: A bearing arrangement for supporting a movable component, in particular the crankshaft, of an internal combustion engine, having at least one bearing for receiving the component and an oil feed line to each bearing, wherein a filter (5) is arranged in the oil feed line (7) directly upstream of the bearing (3).
    Type: Grant
    Filed: August 11, 2000
    Date of Patent: July 30, 2002
    Assignee: Jenbacher Aktiengesellschaft
    Inventor: Gunther Herdin
  • Patent number: 6374950
    Abstract: A lubricant is supplied to a bearing for a rotary shaft by an oil pump capable of discharging the lubricant at different flow rates depending upon its speed of operation. The oil pump is preliminarily operated to allow the user to derive and determine a relationship between temperature rise in the bearing and the flow rate of the lubricant by the oil pump with rate of rotation of the shaft as parameter. An optimum flow rate at which the temperature rise is minimized can be determined from such a relationship. The oil pump is operated such that the lubricant is discharged at this optimum flow rate and according to the current rotary speed of the shaft. Corresponding to different rotary speeds of the shaft, a temperature characteristic curve representing these optimum flow rates of the lubricant can be obtained, and this temperature characteristic curve may be used to vary the speed of operation of the oil pump to change the flow rate of the lubricant according to different rotary speeds of the shaft.
    Type: Grant
    Filed: February 4, 2000
    Date of Patent: April 23, 2002
    Assignees: Mitsui Seiko Kogyo Co., Ltd.
    Inventor: Nakakatsu Takeno
  • Patent number: 6223859
    Abstract: A lubricant feeding system for shaft and hub profile assemblies that can move longitudinally along an axis. A first exterior assembly member (e.g., shaft or hub) encloses at least partly a second interior member (e.g., hub or shaft) along the circumference. At least one distributing channel, extending circumferentially over at least part of the inner circumference, is provided in the region of the profile base. This distributing channel is coupled with at least one lubricant feeding channel extending towards the external circumference of the assembly exterior member The invention includes a distributing member extending circumferentially over the length of the distributing channel, splits the distributing channel into a first partial area located radially outward and a second partial area located radially inward. The distributing member and the distributing channel are designed to form, when they co-operate, a plurality of valve areas between the first and the second partial of the distributing channel.
    Type: Grant
    Filed: June 21, 1999
    Date of Patent: May 1, 2001
    Assignee: Voith Turbo GmbH & Co. KG
    Inventor: Hans Lindenthal
  • Patent number: 5733048
    Abstract: A bearing system includes a lubricant circulation apparatus to provide a continuous supply of lubricant fluid to a bearing device. The bearing device may be a hydrodynamic sleeve bearing having a bearing housing defining a sump for maintaining lubricant fluid therein. An oil ring may be situated about the mechanical shaft supported by the bearing device to deposit oil on top of the shaft during rotation. In addition, a bearing inlet is defined at a location radially above the shaft, with a bearing outlet being defined at a location radially below. The bearing outlet is in fluid communication with a reservoir of the lubricant circulation apparatus. A pump communicates with the reservoir to draw lubricant fluid therefrom and deliver it to the bearing inlet. Preferably, the pump draws lubricant fluid from the reservoir at a rate greater than can be passed through the bearing housing.
    Type: Grant
    Filed: July 29, 1996
    Date of Patent: March 31, 1998
    Assignee: Reliance Electric Industrial Company
    Inventors: Yehia El-Ibiary, Maurice J. D'Hoore
  • Patent number: 5658137
    Abstract: A rotator includes an axle and an associated rotor component having lamellar vanes. A case component surrounds the rotor component. Chambers arranged symmetrically in relation to the axle are disposed between the lamellar vanes. These chambers are pressurized by oil fed through feed and outlet openings connected to the chambers. Bearing members are arranged in an axial direction on both sides of the rotor component. A conical bearing carries the axial rotor load and is formed by a conical arrangement of juxtaposed surfaces defined by the case and axle. The case includes channels leading from the chambers to the conical surfaces for communicating pressurized oil thereamong. The conical arrangement includes spaced gaskets. Oil pressure applied between the conical surfaces raises the axle off the case. In the absence of oil pressure, the conical surfaces lock as a result of friction between the case and axle.
    Type: Grant
    Filed: January 16, 1996
    Date of Patent: August 19, 1997
    Inventor: Jaakko Makela
  • Patent number: 5558446
    Abstract: A "pancake-like" thrust bearing arrangement with gravity-fed lubrication is angular to a horizontal plane and has a top edge above such plane. A load-support structure oscillates on the bearing. Such bearing has a lubricant feed aperture at the top edge and plural lubrication grooves formed in the flat bearing face and connected to such aperture by feed passages. The grooves are oriented so that they "run downhill," i.e., so that they intersect a circle concentric with the bearing center. Grease moves by gravity along the grooves which are "closed-ended" to help prevent premature expulsion of grease from the bearing face.
    Type: Grant
    Filed: June 2, 1995
    Date of Patent: September 24, 1996
    Assignee: Harnischfeger Corporation
    Inventor: Harvey J. Kallenberger
  • Patent number: 5498084
    Abstract: Means and method for restricting the flow of oil which passes between the front bearing and the main shaft of an automatic transmission for motorized vehicles. A gland is formed at the downstream end of the front bearing in either the inner surface of that bearing or of the housing into which the bearing is press-fitted. A split ring made of thermoplastic material having a pressure velocity value in excess of 20,000 at 100 feet/minute surface speed is inserted in the gland and keyed in place against rotation. The ring has a diameter which is slightly less than the diameter of the main shaft which it surrounds, and has circumferential gaps between its overlapping end portions which extend circumferentially 0.006"-0.300" and has axial dimensions of 0.006"-0.150". The circumference of the ring is spaced radially from the opposed wall of the gland at least 0.0005".
    Type: Grant
    Filed: December 14, 1994
    Date of Patent: March 12, 1996
    Assignee: Quadion Corporation
    Inventor: Richard M. Boyd
  • Patent number: 5022769
    Abstract: A static bearing, more particularly a static gas bearing, with a component to be journalled, which is movable with respect to a fixedly arranged bearing part. The bearing part is provided with one or more openings for the supply of a bearing medium between the bearing surfaces facing each other of the component and of the bearing part. The openings communicate with a supply of a bearing medium. A closure member is resiliently arranged opposite each of the supply openings in such a manner that with increasing pressure of the medium in the bearing gap between the surfaces of the component and the bearing part the closure member is moved away from the relevant supply openings and the flow resistance between the supply and the supply opening decreases.
    Type: Grant
    Filed: June 6, 1990
    Date of Patent: June 11, 1991
    Assignee: U.S. Philips Corporation
    Inventors: Johannes A. H. M. Jacobs, Peter L. Holster
  • Patent number: 4983051
    Abstract: A rotary machine 10 includes a rotor shaft 40 and a support system 63 for the shaft. The support system includes a spring 68 and viscous damper 70.Means for removing oil from the damper at preselected rotor speeds is provided and in one embodiment permits operating the engine over a rotor speed range which avoids critical speeds.
    Type: Grant
    Filed: April 11, 1990
    Date of Patent: January 8, 1991
    Assignee: United Technologies Corporation
    Inventors: David H. Hibner, Dennis F. Buono, Kurt M. Dembeck, Roy D. Franceschet
  • Patent number: 4982126
    Abstract: The auxiliary bearing comprises a chromium steel rotor (2) mounted on the rotary shaft (1), a graphite stator (3) mounted on the frame (5) and disposed to face the rotor (2) and to leave clearance relative thereto which is narrower than the air gap in the magnetic bearings which constitute the main supports of the rotary shaft, a network (4) of liquid feed channels opening out into the empty space between the rotor (2) and the stator (3), and selective control means for controlling the supply of liquid through said network of feed channels. The auxiliary bearing may be of the radial clearance type or of the axial clearance type.
    Type: Grant
    Filed: March 31, 1989
    Date of Patent: January 1, 1991
    Assignee: Societe de Mecanique Magnetique S.A.
    Inventors: Jean Jolivet, Helmut Habermann
  • Patent number: 4948270
    Abstract: An oil flushing adapter includes a pair of conduits which are connected at the same point to a bearing support at opposite sides of a rotor, and then pushed apart by an extension device to force the lower ends of the two conduits into sealing contact with a pair of oil outlets. The conduits are then provided with flushing hoses, valves and strainers to sample oil at the bearings for cleanliness, and to shut off oil flow when the oil is sufficiently clean.
    Type: Grant
    Filed: October 16, 1989
    Date of Patent: August 14, 1990
    Assignee: Westinghouse Electric Corp.
    Inventors: Paul G. Minard, Robert C. Hurman, William A. Weiland
  • Patent number: 4887914
    Abstract: An aerostatic bearing with an adjustable stabilizing structure suitable to be applied to a linear sliding rail of a precision test instrument or a precision tool machine, etc., comprises a bearing body with a round or other shaped planes. The plane is furnished with a pocket, a plurality of radial grooves, and a ring-shaped grooves, being in communication with one another. The outer edge of the bearing body is provides with an air intake extended, through an intake passsage, to an area nearing a pocket. The intake passage is in communication with the pocket through a first orifice. A spacing member with a second orifice is movably mounted in the intake passage so as to form a cavity between the two orifices.
    Type: Grant
    Filed: October 26, 1988
    Date of Patent: December 19, 1989
    Assignee: Industrial Technology Research Institute
    Inventors: Yuh-Wen Lin, Ying-Wen Jan
  • Patent number: 4878820
    Abstract: A screw compressor comprises a casing and a pair of male and female rotors respectively having herical teeth and grooves formed in their outer peripheries. The rotors are arranged within the casing in meshing relation to each other through the teeth and grooves. Each rotor is rotatably supported by a pair of first and second radial plain bearings and a thrust plain bearing which is arranged at an end of the rotor shaft and adjacent the second radial plain bearing. Each of the thrust plain bearings is of dynamic-pressure type in which with rotation of a corresponding one of the shafts of the respective rotors, pressure is applied to lubricant by sliding movement of the thrust plain bearing to produce an anti-thrust force.
    Type: Grant
    Filed: May 17, 1988
    Date of Patent: November 7, 1989
    Assignee: Hitachi, Ltd.
    Inventors: Motomichi Doi, Minetoshi Izushi, Kazuhiko Kawaike, Masayuki Urashin
  • Patent number: 4836334
    Abstract: A device for supplying a lubricant to a mechanism, in particular a rolling bearing, comprising a container for holding a quantity of lubricant which at its lower edge is provided with a discharge channel for the lubricant and wherein a spring-loaded piston-like element is located in such fashion that the force of the spring presses this element in the direction of the discharge channel, characterized in that in the discharge channel is mounted a valve member, normally found in the closed position, which is coupled with an electric circuit which upon excitation controls the valve member bringing this valve member into the open and again into the closed position.
    Type: Grant
    Filed: June 1, 1987
    Date of Patent: June 6, 1989
    Assignee: SKF Industrial Trading and Development Co., B.V.
    Inventor: Johan C. M. Bras
  • Patent number: 4806075
    Abstract: A single-ended turbomolecular vacuum pump operable in the free molecular flow pressure range having an improved bearing assembly located between the motor and the pump rotor discs is disclosed. The improved bearing assembly which is of the "plain" or "sleeve" liquid lubricated type with the bearing surfaces has a relatively high ratio of journal diameter to bearing axial length and includes lubricant ports radially disposed about both the centers of the bearing and the journal. The improved bearing assembly is characterized by improved heat transmission capabilities, high tolerance for misalignment, long life and significant reduction of pump vibration.
    Type: Grant
    Filed: December 15, 1986
    Date of Patent: February 21, 1989
    Assignee: Sargent-Welch Scientific Co.
    Inventors: Gordon E. Osterstrom, Leonid Livshits, Mark B. Renz
  • Patent number: 4758100
    Abstract: An automatic lubricant metering device consists essentially of a housing (4), from inside of which a piston (5) is conveying a lubricant (15) through a feeder line (12) to the lubricating location (2) of a revolving shaft (1). The automatic feature consists of that the spring-loaded piston (5) is connected with a pin (6) made of an abradable material. The advance of the piston (5) is a function of the abrasion of the pin (6) on the appropriately roughened surface of the shaft. The lubricant is contained in a compressible bellows (11) equipped with a feeder line (12) to the lubricating location (2). The feed to the lubricating location is conducted in the area of the shaft through a pipe (13) located preferably without contact in a center bore (14) of the shaft. The outlet of this pipe opens into a radial bore (16) connected with the lubricating location (16).
    Type: Grant
    Filed: September 23, 1987
    Date of Patent: July 19, 1988
    Assignee: Aginfor AG fur industrielle Forschung
    Inventor: Frank Guttinger
  • Patent number: 4696585
    Abstract: A control system for bypassing critical speeds in a high speed rotating turbine shaft supported by multiple journal bearings which includes pairs of apertures disposed in each bearing seat. The pairs of apertures are linked by fluid vent lines having valves disposed therein. The valves are responsive to vibration in the shaft and serve to vent lubricant between opposing apertures in order to vary the stiffness and hence the spring rate of the bearing as the shaft approaches critical speed.
    Type: Grant
    Filed: January 17, 1986
    Date of Patent: September 29, 1987
    Inventor: Judson S. Swearingen
  • Patent number: 4690572
    Abstract: A static pressure gas bearing apparatus equipped with a static pressure gas bearing that can support in floated state the rotating shaft of the turbocharger to be placed on an internal combustion engine comprises an air pump device for pressurizing and supplying a gas, an accumulator for storing the pressurized gas supplied form the air pump device, a pressurized gas supply passage device for connecting the accumulator to the static pressure gas bearing, a bypass passage device for connecting the air pump device to the static pressure gas bearing by bypassing the accumulator, and a control device for controlling the opening and the closing of the bypass passage device in response to the internal pressure of the accumulator.
    Type: Grant
    Filed: October 31, 1986
    Date of Patent: September 1, 1987
    Assignee: Nissan Motor Co., Ltd.
    Inventor: Naoto Sasaki
  • Patent number: 4624584
    Abstract: The bearing sliding surface of the sliding journal bearing is composed of two surface parts of two circular cylinders whose axes are located at a distance apart. A diametral plane defined by the two axes of these circular cylinders includes, together with a horizontal plane through the bearing axis, an angle of approximately At least one oil supply hole enters into each bearing bore underneath and above the horizontal plane and is displaced in the rotational direction of the shaft by approximately the same angle relative to the horizontal plane. A throttle can be provided in a pipe upstream of the upper oil supply hole.
    Type: Grant
    Filed: June 12, 1984
    Date of Patent: November 25, 1986
    Assignee: BBC Brown, Boveri & Company, Limited
    Inventor: Robert Odermatt
  • Patent number: 4624586
    Abstract: A bearing for a large rotating shaft machine is subject to differing conditions of operations. In order to accommodate these differing conditions of operation, the lubricant flows throughout the bearings may have to be changed. The prior art method of changing flow distributions throughout a bearing would be to remachine orifice passageways formed in the base ring. The present invention overcomes this difficulty by proposing a standardized base ring and multi-variable orifices which can be remachined and reinserted into the base ring with minimal difficulty and machining.
    Type: Grant
    Filed: March 1, 1985
    Date of Patent: November 25, 1986
    Assignee: General Electric Company
    Inventor: Robert W. Brogan
  • Patent number: 4621931
    Abstract: A method and apparatus for regulating the flow of liquid lubricant to hydrostatic bearings is disclosed. A cavitating venturi is utilized to regulate the volume flow rate of liquid lubricant supplied to a bearing. The cavitating venturi acts to provide a constant volume flow rate of liquid lubricant relatively independent of system flow resistance and feed pressure to the bearing.
    Type: Grant
    Filed: December 19, 1983
    Date of Patent: November 11, 1986
    Assignee: Elliott Turbomachinery Co., Inc.
    Inventor: Richard C. Jensen
  • Patent number: 4455098
    Abstract: A self-pumping thrust bearing for electric machines having a vertical shaft is disclosed in which oil circulates through radially-extending bores in a rotating thrust ring to suck hot oil from an oil space and transfer it to a ring canal disposed in a stationary part. In order to make the transition from the rotating thrust ring to the stationary ring canal as loss free as possible, there is arranged on the outside at the thrust ring a circular canal into which the bores lead. This circular canal is bounded on the side facing the stationary part by a height-adjustable ring which is held at the thrust ring with a gap between the ring and the thrust ring. The transfer of oil therefore takes place around the entire circumference of the thrust ring so that turbulence is avoided. The quantity of oil pumped can be adjusted by adjusting the width of the gap.
    Type: Grant
    Filed: September 30, 1982
    Date of Patent: June 19, 1984
    Assignee: Siemens Aktiengesellschaft
    Inventor: Hans-Jurgen Pollok
  • Patent number: 4381127
    Abstract: The invention relates to the combination of a radial bearing 4,5;38,39 and a seal 14,17,21; 42,45,46 which both make use of elastomeric bushings 6,7,17,42,45 having a smooth cylindrical surface supporting a shaft (1,36) provided with helical grooves 10,11,15,19,46 conveying the lubricating liquid said helical grooves conveying in the same or opposite directions, said combination of radial bearing and seal further can be combined with an axial bearing 40 having grooves in a disc 53 which rotates with the shaft (36) and which is in engagement with stationary discs 54,55 of elastomeric material.
    Type: Grant
    Filed: April 16, 1981
    Date of Patent: April 26, 1983
    Assignee: IHC Holland N.V.
    Inventor: Teunis Visser