Compact fluid motor control system with float position

Claim 2

In a control system for a fluid motor (10) which has first and second motor ports (11, 12) wherein admission of pressurized fluid to said first motor port causes motor operation in one direction and admission of pressurized fluid to said second motor port causes motor operation in the opposite direction, the combination comprising: a directional control valve (17) having an inlet passage (59) for receiving pressurized fluid and having a discharge passage (74) and first and second outlet passages (69, 64) for connection to said first and second motor ports respectively and having a valve member (19) movable between a first motor operating position at which fluid from said inlet is transmitted to said first outlet while said second outlet is communicated with said discharge passage and a second motor operating position at which fluid from said inlet is transmitted to said second outlet while said first outlet is communicated with said discharge passage, and further having pilot means (51, 54) for shifting said valve member between said positions in response to fluid pilot pressure signals, make-up valve means disposed in a bypass passage (75) between at least one of said outlet passages of said directional control valve and said discharge passage and Having a first make-up valve member (78) movable to close said bypass passage and having means forming a first chamber (84) wherein fluid pressure derived from said one outlet passage acts against said first make-up valve member to urge said first make-up valve member towards the position at which said bypass passage is closed, and a pilot valve (25) having an inlet passage (56) for receiving pressurized fluid and a discharge passage (37) and an outlet means (33) communicated with said pilot means of said directional control valve for transmitting said fluid pilot pressure signals thereto to shift said valve member of said directional control valve, said pilot valve further having a valve member (31) movable between a plurality of motor operating positions for selectively transmitting said pilot pressure signals to said directional control valve, and being further movable to a float position, said pilot valve having venting means (36, 91, 95) for communicating said first chamber of said make-up valve means with said pilot valve means discharge passage upon said movement of said pilot valve member to said float position.

Claim 3

The combination defined in claim 1 wherein said first make-up valve member has a flow orifice (85) therethrough to transmit said fluid pressure of said one outlet passage of said directional control valve to said first chamber.

Claim 4

The combination defined in claim 1 wherein said first make-up valve member has a shoulder (87) thereon exposed to the fluid pressure of said one outlet passage.

Claim 5

The combination defined in claim 1 wherein said pilot valve means has means (35, 49) for transmitting said pressure signals to said directional control valve pilot means to shift said valve member of said directional control valve to one of said motor operating positions thereof while said pilot valve member is at said float position thereof and said pilot valve means is communicating said first chamber of said directional control valve with said discharge passage of said pilot valve means.

Claim 6

The combination defined in claim 1 wherein said make-up valve means further comprises means forming a second bypass flow passage (75a) between the other outlet passage (64) of said directional control valve and said discharge passage thereof, a second make-up valve member (79) movable to close said second bypass passage, means forming a second chamber (88) wherein fluid pressure derived from said other outlet passage acts against said second make-up valve member to urge said second make-up valve member to close said second bypass passage, a float valve (93) connected between said second chamber and said venting means, and means for opening said blocker valve in response to an unpressurized condition in said outlet means of said pilot valve means whereby said pilot valve means communicates said second chamber to said pilot valve discharge passage if said pilot valve member is at said float position and said fluid pilot pressure signal is absent.

Claim 7

The combination defined in claim 5 wherein said float valve is connected between said venting means and both said first and second chambers and is spring biased towards a first position wherein said second chamber is communicated with said venting means while said first chamber is blocked therefrom, further comprising pilot means responsive to said fluid pilot pressure to urge said float valve to a second position at which said first chamber is communicated with said venting means while said second chamber is blocked therefrom.

Claim 8

In a control system for a fluid motor having a first port to which pressurized fluid is supplied to drive said motor in a first direction and having a second port to which pressurized fluid is supplied to drive said motor in an opposite direction, the combination comprising: a directional control valve having a valve body with an inlet passage for receiving the pressurized fluid and first and second outlet passages for connection to said first and second motor ports respectiveLy and a discharge passage for discharging fluid, said valve body having a bore therein, said directional control valve having a first spool movable in said bore between a centered Hold position at which both of said outlet passages are blocked from said inlet passage and said discharge passage and having a first operating position at which said inlet passage is communicated with said first outlet passage while said second outlet passage is communicated to said discharge passage and having a second motor operating position at which said inlet passage is communicated with said second outlet passage while said first outlet passage is communicated with said discharge passage, and having spring means for urging said first spool towards said Hold position thereof; make-up valve means having means forming a first bypass passage between said first outlet passage and said discharge passage and having means forming a second bypass passage between said second outlet passage and said discharge passage and having first and second make-up valve members disposed in said first and second bypass passages respectively each being movable to close the associated bypass passage, and having means defining a first chamber communicated with said first outlet passage through a flow restriction to receive fluid pressure therefrom wherein said fluid pressure acts against an area of said first make-up valve member to urge said first make-up valve member towards the position at which said first bypass passage is closed, and having means for causing said fluid pressure of said outlet passage to act directly on a smaller area of said first make-up valve member in a direction tending to cause said make-up valve member to open said first flow passage, and having means forming a second chamber receiving fluid pressure from said second outlet passage through a second flow restriction wherein said fluid pressure acts on an area of said second make-up valve member in a direction tending to cause said second make-up valve member to close said second bypass passage, and having means causing said pressure of said second outlet passage to act directly on a smaller area of said second make-up valve member in a direction tending to cause said second make-up valve member to move to open said second bypass passage, and a manually operated pilot valve for transmitting fluid pressure to said directional control valve to control said directional control valve, said pilot having a valve body with a pressurized fluid inlet and first and second outlet means communicated with opposite ends of said bore of said directional control valve and having a discharge passage and having a bore within said body, said pilot valve having a pilot valve spool movable in said bore between at least four positions including one position at which both of said outlet means are communicated with said discharge passage enabling said directional control valve spool to assume said Hold position thereof, and including a first motor operating position at which one of said outlet means is communicated with said inlet passage while the other of said outlet means is communicated with said discharge passage causing said directional control valve spool to assume said first of said motor operating positions thereof and including a second motor operating position at which the other of said outlet means is communicated with said inlet passage while said one outlet means is communicated with said discharge passage enabling said spool of said directional control valve to assume said second motor operating position thereof and further including a float position at which one of said outlet means is communicated with said inlet passage while the other of said outlet means is communicated with said discharge passage and while one of said chambers of said make-up valve means is also communicated with said discharge passage.

Claim 9

In a control system for a fluid motor having a first port to which pressurized fluid is supplied to drive said motor in a first direction and having a second port to which pressurized fluid is supplied to drive said motor in an opposite direction, the combination comprising: a directional control valve having a valve body with an inlet passage for receiving the pressurized fluid and first and second outlet passages for connection to said first and second motor ports respectiveLy and a discharge passage for discharging fluid, said valve body having a bore therein, said directional control valve having a first spool movable in said bore between a centered Hold position at which both of said outlet passages are blocked from said inlet passage and said discharge passage and having a first operating position at which said inlet passage is communicated with said first outlet passage while said second outlet passage is communicated to said discharge passage and having a second motor operating position at which said inlet passage is communicated with said second outlet passage while said first outlet passage is communicated with said discharge passage, and having spring means for urging said first spool towards said Hold position thereof; make-up valve means having means forming a first bypass passage between said first outlet passage and said discharge passage and having means forming a second bypass passage between said second outlet passage and said discharge passage and having first and second make-up valve members disposed in said first and second bypass passages respectively each being movable to close the associated bypass passage, and having means defining a first chamber communicated with said first outlet passage through a flow restriction to receive fluid pressure therefrom wherein said fluid pressure acts against an area of said first make-up valve member to urge said first make-up valve member towards the position at which said first bypass passage is closed, and having means for causing said fluid pressure of said outlet passage to act directly on a smaller area of said first make-up valve member in a direction tending to cause said make-up valve member to open said first flow passage, and having means forming a second chamber receiving fluid pressure from said second outlet passage through a second flow restriction wherein said fluid pressure acts on an area of said second make-up valve member in a direction tending to cause said second make-up valve member to close said second bypass passage, and having means causing said pressure of said second outlet passage to act directly on a smaller area of said second make-up valve member in a direction tending to cause said second make-up valve member to move to open said second bypass passage, and a manually operated pilot valve for transmitting fluid pressure to said directional control valve to control said directional control valve, said pilot having a valve body with a pressurized fluid inlet and first and second outlet means communicated with opposite ends of said bore of said directional control valve and having a discharge passage and having a bore within said body, said pilot valve having a pilot valve spool movable in said bore between at least four positions including one position at which both of said outlet means are communicated with said discharge passage enabling said directional control valve spool to assume said Hold position thereof, and including a first motor operating position at which one of said outlet means is communicated with said inlet passage while the other of said outlet means is communicated with said discharge passage causing said directional control valve spool to assume said first of said motor operating positions thereof and including a second motor operating position at which the other of said outlet means is communicated with said inlet passage while said one outlet means is communicated with said discharge passage enabling said spool of said directional control valve to assume said second motor operating position thereof and further including a float position at which one of said outlet means is communicated with said inlet passage while the other of said outlet means is communicated with said discharge passage and while one of said chambers of said make-up valve means is also communicated with said discharge passage.

Claim 10

The combination defined in claim 7 further comprising a float valve connected between said pilot valve and both of said chambers of said make-up valve means, a spring biasing said float valve towards a first position at which said one chamber is blocked from said pilot valve while the other of said chambers is communicated therewith, and pilot means for causing said pressurized fluid to urge said float valve towards a second position at which said one chamber is communicated with said pilot valve while said other chamber is blocked therefrom, and means in said pilot valve for venting the one of said chambers which is connected therewith when said pilot valve is at said float position thereof.