Valve mechanism
A valve mechanism ( 3 ) for attaching to a proximal end ( 4 ) of a trocar cannula ( 2 ) for minimising leakage of insufflating and other gases proximally from the trocar cannula ( 2 ), comprises a housing ( 7 ) adapted for securing to the trocar cannula ( 2 ) adjacent the proximal end ( 4 ) thereof. The housing ( 7 ) defines an instrument bore ( 22 ) extending from a proximal end ( 23 ) to a distal end ( 21 ). A distal valve ( 28 ) is located adjacent the distal end ( 21 ) of the instrument bore ( 22 ) and is pivotal from an open state to a closed state. A proximal valve ( 40 ) is located towards the proximal end ( 23 ) of the instrument bore ( 22 ), and comprises first and second valve members ( 41 ) and ( 42 ) which are urgeable from a withdrawn state clear of the instrument bore ( 22 ) to an engagement state sealably engaging an instrument in the instrument bore ( 22 ) for sealing the instrument bore ( 22 ). A detecting probe ( 34 ) pivotal about a primary pivot axis ( 35 ) is urgeable distally from a first state to a second state by the distal end of an instrument passing distally through the instrument bore ( 22 ). A drive transmission ( 74,108 ) transmits drive from the detecting probe ( 34 ) to the proximal and distal valves ( 40,28 ), so that as the detecting probe ( 34 ) is urged from a first state to a second state the distal valve ( 28 ) is urged into the open state and the proximal valve ( 40 ) is simultaneously urged from the withdrawn state to the engagement state to minimise leakage of gas proximally through the instrument bore ( 22 ) and to minimise contact of an instrument with the proximal and distal valves ( 40,28 ).
1 . A valve mechanism for a trocar or a trocar cannula, the valve mechanism comprising:
a housing having an instrument bore extending therethrough from a proximal end to a distal end and defining a longitudinally extending main central axis,
a detecting means located in the housing configured to detect an instrument in or passing through the instrument bore,
a proximal valve located in the housing proximally of the detecting means and being operable from a withdrawn state to an engagement state engaging the instrument in the instrument bore to form a seal with the instrument for minimising leakage of gas past the proximal valve in response to the detecting means detecting an instrument passing distally in the instrument bore, and
a distal valve located distally of the detecting means operable from a closed state closing the instrument bore to an open state permitting passage of an instrument through the instrument bore in response to the detecting means detecting an instrument passing distally in the instrument bore, so that as the distal valve is operating from the closed state to the open state, the proximal valve is simultaneously operating from the withdrawn state to the engagement state.
2 . A valve mechanism as claimed in claim 1 in which the detecting means is configured to extend into the instrument bore for engaging an instrument in the instrument bore.
3 . A valve mechanism as claimed in claim 2 in which the detecting means is moveably mounted in the housing, and is moveable in the instrument bore from a first state to a second state in response to movement of an instrument distally in the instrument bore.
4 . A valve mechanism as claimed in claim 3 in which the proximal valve is urgeable from the withdrawn state to the engagement state and the distal valve is urgeable from the closed state to the open state in response to movement of the detecting means from the first state to the second state.
5 . A valve mechanism as claimed in claim 3 in which the detecting means is configured to be urgeable from the first state to the second state by movement of an instrument distally in the instrument bore.
6 . A valve mechanism as claimed in claim 3 in which a first transmission means is provided for transmitting movement of the detecting means from the first state to the second state to movement of the proximal valve from the withdrawn state to the engagement state, and a second drive transmission means is provided for transmitting movement of the detecting means from the first state to the second state to movement of the distal valve from the closed state to the open state.
7 . A valve mechanism as claimed in claim 6 in which the first transmission means comprises a first drive transmission means.
8 . A valve mechanism as claimed in claim 2 in which the detecting means is configured to engage a distal end of an instrument in the instrument bore.
9 . A valve mechanism as claimed in claim 1 in which the proximal valve comprises a pair of proximal valve elements urgeable from the withdrawn state to the engagement state for engaging an instrument in the instrument bore.
10 . A valve mechanism as claimed in claim 9 in which the proximal valve elements of the pair thereof are moveable between the withdrawn state and the engagement state transversely relative to the main central axis.
11 . A valve mechanism as claimed in claim 9 in which the proximal valve elements of the pair thereof are located on respective opposite sides of the main central axis, and are moveable towards each other from the withdrawn state to the engagement state.
12 . A valve mechanism as claimed in claim 1 in which an urging means is provided for urging the proximal valve into the withdrawn state and for urging the distal valve into the closed state.
13 . A valve mechanism as claimed in claim 12 in which the urging means comprises a resilient urging means.
14 . A valve mechanism as claimed in claim 12 in which the urging means is responsive to a distal end of an instrument in the instrument bore passing proximally past the detecting means for urging the proximal valve from the engagement state to the withdrawn state and for urging the distal valve from the open state to the closed state.
15 . A valve mechanism as claimed in claim 1 in which the distal valve is located adjacent the distal end of the instrument bore.
16 . A valve mechanism as claimed in claim 1 in which the valve mechanism is configured for mounting on a proximal end of a trocar or a trocar cannula with the instrument bore defined by the housing of the valve mechanism aligned with an instrument bore of the trocar or the trocar cannula.
17 . An assembly comprising a trocar or a trocar cannula and the valve mechanism as claimed in claim 1 mounted on the trocar or the trocar cannula adjacent the proximal end thereof.
18 . A valve mechanism as claimed in claim 1 in which the detecting means is pivotally mounted in the housing about a primary pivot axis, the primary pivot axis extending transversely relative to the main central axis defined by the instrument bore.
19 . A valve mechanism as claimed in claim 18 in which the distal valve is pivotal about a distal valve pivot axis, and the distal valve pivot axis extends transversely of the main central axis defined by the instrument bore and parallel to the primary pivot axis.
20 . A valve mechanism as claimed in claim 1 in which the housing terminates in a valve seat adjacent the distal end of the instrument bore and the distal valve is sealably engageable with the valve seat in the closed state.