Patents by Inventor Ian T. Bristow

Ian T. Bristow has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 4679995
    Abstract: A variable-capacity roller- or vane-type pump has a cam ring which is movable to vary the delivery of the pump and means is provided for applying to the movement of the cam ring a damping force which varies in dependence upon the instantaneous position of the cam ring.
    Type: Grant
    Filed: July 5, 1985
    Date of Patent: July 14, 1987
    Assignee: Hobourn-Eaton, Ltd.
    Inventor: Ian T. Bristow
  • Patent number: 4673341
    Abstract: A roller or vane type pump is described of the kind in which the cam ring is pivotally mounted within an external casing to vary the throw of the cam ring and hence the pump delivery means is provided whereby a constant flow is obtained regardless of the pump speed. The cam surface of the cam ring is not wholly circular. The two portions of the cam surface extending between the inlet and outlet ports of the pump at opposite sides respectively of the pump axis have curvatures such that the instantaneous distance R.sub.2 of the point of contact of one of the sealing rollers or vanes with the cam surface from the axis of rotation of the rotor is given by R.sub.2 =.sqroot.R.sub.1.sup.2 +k where k is a constant and R.sub.1 is a corresponding instantaneous distance of the point of contact of the other sealing roller or vane with the cam surface from said axis.
    Type: Grant
    Filed: July 5, 1985
    Date of Patent: June 16, 1987
    Assignee: Hobourn-Eaton Limited
    Inventor: Ian T. Bristow
  • Patent number: 4659296
    Abstract: The cam surface of a roller-type positive displacement pump providing an inlet port and two outlet ports has on circumferentially opposite sides of at least one of the outlet ports a profile such that the difference between the squares of the radii at the instantaneous points of contact therewith of the two rollers which serve to seal the port at said opposite sides is a constant. The portions of the cam surface at oposite sides of such an outlet port have radii relative to the axis of rotation of the rotor which decrease progressively in the direction of rotation of the rotor.
    Type: Grant
    Filed: October 30, 1985
    Date of Patent: April 21, 1987
    Assignee: Hobourn-Eaton Limited
    Inventor: Ian T. Bristow
  • Patent number: 4426196
    Abstract: A pumped oil supply system, for example for lubricating an internal combustion engine incorporates a relief valve the control element of which has superimposed thereon an opening force derived from a temperature responsive element responsive to the temperature of the oil delivered by the pump part of the system. The pump part has separate first and second outlets, the second outlet communicating with the oil gallery of the engine and the first outlet communicating with the second outlet through a variable restrictor. The first outlet has a relief valve with a spring-loaded piston acted on by the delivery pressure in the first outlet, and the piston is connected to a center body constituting the adjustable member of the variable restrictor. The temperature responsive element is disposed in the second outlet and imposes a resilient force on the piston which, with increase of the oil temperature, augments the action thereon of the delivery pressure in the first outlet.
    Type: Grant
    Filed: September 16, 1981
    Date of Patent: January 17, 1984
    Assignee: Hobourn-Eaton Limited
    Inventors: Ian T. Bristow, Peter A. E. Wilson
  • Patent number: 4391569
    Abstract: To minimize the power absorbed by a positive displacement pump system used where the requirement for pressure fluid varies inversely with the pump speed, notably in automobiles, the system provides two separate delivery passages 61, 62 for the pumped fluid and a discharge passage 66 into which the fluid from the delivery passage is passed under the control of a valve means 70, 71, the valve means commencing to operate on one (62) of the two delivered flows at lower speeds to by-pass a proportion of said one flow to an overspill 79, while the fluid not bypassed is added to the flow from the other delivery passage being passed to the discharge passage.
    Type: Grant
    Filed: December 10, 1979
    Date of Patent: July 5, 1983
    Assignee: Hobourn-Eaton Limited
    Inventors: Ian T. Bristow, Alec Thornelow
  • Patent number: 4360322
    Abstract: A positive displacement pump system has two delivery passages communicating under the control of a valve with a main discharge passage and/or an overspill duct. The valve is constituted by a valve member slidably mounted in a valve bore and the valve member has lands and intermediate recesses controlling communication between the delivery passages and the overspill duct. The pressures upstream and downstream of a discharge orifice in the discharge passage are applied to the valve member in opposition to each other, increase of the pressure drop tending to move the valve member to increase the amount of fluid passed to the overspill duct. To overcome the known tendency for a valve member to be subjected by the hydraulic forces to a large closing force when the valve is open to only a small extent, the valve is designed to provide for a relatively large opening force at least when the valve is commencing to open.
    Type: Grant
    Filed: December 10, 1979
    Date of Patent: November 23, 1982
    Assignee: Hobourn-Eaton Limited
    Inventors: Ian T. Bristow, Nigel J. Petts
  • Patent number: 4340337
    Abstract: A positive displacement pump system has first and second delivery passages for the pumped fluid and a main discharge passage. A control valve operating in dependence on the pressure drop across an orifice in the discharge passage diverts through overspill porting a proportion of the flow through the second delivery passage, the remainder added to the flow from the first delivery passage and passed to the discharge passage. The control valve also regulates the by-passing of a proportion of the flow from the first delivery passage to the overspill porting. As the said pressure drop increases, the control valve first increases the proportion of the flow from the second delivery passage diverted to the overspill porting and, as the pressure drop increases further, then commences to by-pass fluid from the first delivery passage to the overspill port, the quantity by-passed increasing with increase of said pressure drop.
    Type: Grant
    Filed: December 10, 1979
    Date of Patent: July 20, 1982
    Assignee: Hobourn-Eaton Limited
    Inventors: Ian T. Bristow, Nigel J. Petts
  • Patent number: 4298315
    Abstract: A positive displacement pump system provides first and second delivery 11, 12 passages of which the first passage 11 communicates with a main discharge passage 15 containing a discharge orifice 17. The second delivery passage 12 opens to a valve bore and is in permanently open communication with the first delivery passage through an axial passage 29 in a valve member 20 slidably mounted in the valve bore. Lifting of the valve member with increasing pressure drop across the orifice 17 places the first delivery passage in communication with an overspill port 14. The pressure at the upstream and downstream sides of the orifice are applied against the lower end and the upper end 28 of the valve member so that the valve operates to maintain the pressure difference constant. The pressure difference between passage 29 and that applied against the upper end 28 of the valve member is therefore also substantially constant, so that leakage from passage 29 past the upper end 28 is constant.
    Type: Grant
    Filed: December 10, 1979
    Date of Patent: November 3, 1981
    Assignee: Hobourn-Eaton Limited
    Inventors: Ian T. Bristow, Nigel J. Petts