Mechanical seal with automatic gap convergence control

A controllable mechanical seal for sealing a shaft rotatable relative to the housing of a fluid machine, said seal comprising a first face element having a first radial face surface, said first element being adapted for rotation with the shaft, a second face element having a second radial face surface, said second element being adapted to be supported within the housing, one of said elements being movable axially along the shaft, said first and second surfaces being adapted to define a gap within which there is a thin lubricating fluid film, a piezoelectric actuator coupled to one of said elements to deform its surface so that the gap converges in a direction from a high pressure side to a low pressure side of said seal, a thermocouple imbedded in one of said elements for measuring a temperature indicative of incipient contact of said surfaces, and a control system responsive to the temperature measurement for generating a voltage which is applied to said piezoelectric actuator to control the convergence of the surfaces and thus maintain an optimum thickness of the lubricating film for a wide range of operating conditions.

A controllable mechanical seal for a fluid machine having a housing and a shaft rotatable relative to the housing, said seal comprising a first face element rotatable with the shaft, a second face element supported by the housing, said first and second elements respectively defining first and second face surfaces, one of said elements being slidable along the shaft toward and away from the other of said elements to establish a gap between said surfaces, means biasing said one element toward said other element, said elements at a given operating condition of the machine having a degree of convergence substantially equal to the convergence of said surfaces divided by the average width of said gap, and means for adjusting the convergence of said surfaces to thereby change the width of said gap.

A controllable mechanical seal for a fluid machine having a housing and a shaft rotatable relative to the housing, said seal comprising a first face element rotatable with the shaft, a second face element supported by the housing, said first and second elements respectively defining first and second face surfaces, one of said elements being slidable along the shaft toward and away from the other of said elements to establish a gap between said surfaces, means biasing said one element toward said other element, said elements at a given operating condition of the machine having a degree of convergence substantially equal to the convergence of said surfaces divided by the average width of said gap, means for sensing a change in the width of said gap indicative of a change in the machine operating condition, and means responsive to the sensed change for adjusting the convergence of said surfaces such that the gap width is changed, whereby said seal compensates for the change in the machine operating condition.