| 主权项 |
1. Valve with a spool for the control of the start and of the stop of a hydraulic motor in which an oblong spool is mobile within an oblong seat obtained in a body, the movement of said spool being controllable in two opposite directions of movement of said spool by means of control means, said spool being housed within an intermediate portion of said seat in which said intermediate portion has a section size that is essentially equal to the section size of said spool, said control means being a pair of control channels comprising a first control channel and a second control channel that flow respectively into a first chamber and into a second chamber obtained within said body in correspondence of opposite sides with respect to a third chamber comprising said intermediate portion of said seat, said first control channel constituting a channel for the control of the movement of said spool in a first control direction, said second control channel constituting a channel for the control of the movement of said spool in a second control direction, said control means being suitable for the movement of said spool between:
a first position that is a displacement position of said spool in a first direction; a second position that is a displacement position of said spool in a second direction opposite to said first direction; a third position that is an essentially central position of said spool within said intermediate portion of said seat;said spool being provided with at least one intermediate part with respect to a first end and to a second end of said spool in which said at least one intermediate part has a smaller section size than the section size of said intermediate portion of said seat giving rise to the formation of an interstice, characterized in that said interstice reciprocally connects at least one first duct and at least one second duct that are independent and separate ducts with respect to said first control channel and said second control channel, said interstice being intended for the passage of a fluid between said first duct and second duct according to the following conditions:
in said first position that is a displacement position of said spool in said first direction, to said displacement of said spool corresponding a displacement of said interstice that enters a condition of non-connection between said first duct and said second duct, in said second position that is a displacement position of said spool in said second direction opposite to said first direction, to said displacement of said spool corresponding a displacement of said interstice that enters a condition of non-connection between said first duct and said second duct; in said third position that is an essentially central position of said spool within said intermediate portion of said seat, said interstice being in a condition of connection between said first duct and said second duct;said valve (1) being further characterised in that the passage of said spool from a position selected from:
said first position that is a displacement position of said spool in said first direction; said second position that is a displacement position of said spool in said second direction opposite to said first direction;towards said third position that is an essentially central position of said spool within said intermediate portion of said seat occurs by means of a pair of elastic means comprising:
a first elastic means exerting a reaction force opposing to the displacement movement of said spool in said first displacement direction; a second elastic means exerting a reaction force opposing to the displacement movement of said spool (4) in said second displacement direction,in which said first elastic means and said second elastic means act one against the other, the two elastic means exerting their force on said spool in an opposite direction, said two elastic means and said spool being structured so that part of this force is released on the body and it is transferred entirely to the spool only when said spool leaves said third position that is an essentially central position of said spool, in said central position of said spool said two elastic means acting one against the other so that said spool will settle in the position in which the force of the two elastic means is balanced. |
