US 4,541,451 AGranted

Priority valve

AssigneeDeere & Company

InventorsRichard A. Wittren, James A. Miller

Life of this patent

Estimating the term…

Loading patent…

Abstract

A priority valve is disclosed for controlling fluid flow between a power source and a priority function and secondary function operated by the power source. The priority valve includes a housing having first and second bores formed therein. An inlet passage connects the power source to the first bore while first and second outlet passages connect the first bore to the primary and secondary functions respectively. A valve spool is positioned in the first bore and is movable between a first position permitting fluid flow from the inlet passage to the first outlet passage while blocking fluid flow to the second outlet passage and a second position permitting fluid flow from the inlet passage to the second outlet passage while blocking fluid flow to the first outlet passage. A pin is movably positioned in the second bore and has an enlarged end which extends into the first bore. a load signal passage connects the priority function to the second end of the first bore. When full fluid flow is demanded by the priority function the valve spool moves toward its first position. When the priority valve demands less than full flow, the spool valve moves toward its second position. If the priority function demands pressure approaching a maximum pressure value which can be delivered by the power source the enlarged end of the pin contacts the valve spool and forces it toward its second position.

Claims11

Dependent claims

A priority valve for controlling fluid flow between a power source and functions operated by said power source, one of said functions being a priority function and at least one other function being a secondary function, said valve comprising:

(a) a housing having first and second bores formed therein;
(b) an inlet passage connecting said power source to said first bore and first and second outlet passages connecting said first bore to said priority and secondary functions, respectively;
(c) a valve spool positioned in said first bore so as to divide said first bore into first and second ends, said valve spool having an annular groove which is in constant communication with said inlet passage and with at least one of said outlet passages, and a passageway formed therein having a first opening which is in constant communication with said first end of said first bore and a second opening which is in constant communication with said first outlet passage, said valve spool being movable between a first position wherein said annular groove is in communication with said first outlet passage while said valve spool blocks fluid flow to said second outlet passage from communication with said annular groove, and a second position wherein said annular groove is in communication with said second outlet passage, while said valve spool blocks said first outlet passage from communication with said annular groove;
(d) a pin movably positioned in said second bore having an enlarged end which extends into said second end of said first bore;
(e) biasing means for urging said valve spool toward said first position and said pin toward said valve spool;
(f) means carried by said valve spool for engagement with said pin after limited movement of said pin relative to and in a direction away from said valve spool;
and
(g) a load signal passage establishing fluid communication between said priority function and said second end of said first bore, which fluid acts to urge said valve spool toward said first position and said pin out of said first bore such that a decrease in pressure difference between said load signal passage and said inlet passage urges said valve spool toward said first position, an increase in pressure difference between said load signal passage and said inlet passage allows said valve spool to move toward said second position, and a predetermined maximum fluid pressure within said load signal passage causes said pin to move out of said first bore engaging and moving said spool toward said second position.

5 more elements

A priority valve for controlling fluid flow between a power source and hydraulic functions operated by said power source, one of said hydraulic functions being a priority function and at least one other function being a secondary function, said valve comprising:

(a) a housing having first and second bores formed therein;
(b) an inlet passage connecting said power source to said first bore and first and second outlet passages connecting said first bore to said priority and secondary functions, respectively;
(c) a valve spool positioned in said first bore so as to divide said first bore into first and second ends, said valve spool having an annular groove which is in constant communication with said inlet passage and with at least one of said outlet passages, and a passageway formed therein having a first opening which is in constant communication with said first end of said first bore and a second opening which is in constant communication with said first outlet passage, said valve spool being movable between a first position wherein said annular groove is in communication with said first outlet passage, while simultaneously sealing said second outlet passage from communication with said annular groove, and a second position wherein said annular groove is in communication with said second outlet passage, while simultaneously sealing said first outlet passage from communication with said annular groove;
(d) a pin movably positioned in said second bore having an enlarged end which extends into said second end of said first bore;
(e) first and second springs positioned in said first bore for urging said valve spool toward said first position and said pin toward said valve spool;
(f) means for engaging said pin with said spool valve after limited free movement of said pin out of said first bore;
and
(g) a load signal passage establishing fluid communication between said priority function and said second end of said first bore which fluid acts to urge said valve spool toward said first position and said pin out of said bore such that a decrease in pressure difference between said load signal passage and said inlet passage urges said valve spool toward said first position, an increase in pressure difference between said load signal passage and said inlet passage allows said valve spool to move toward said second position, and a predetermined maximum fluid pressure within said load signal passage causes said pin to move out of said first bore engaging and moving said spool toward said second position.

5 more elements

(a) a housing having first and second bores formed therein and a spring cavity communicating with said second bore which is connected to a fluid reservoir;
(b) an inlet passage connecting said power source to said first bore and first and second outlet passages connecting said first bore to said priority and secondary functions, respectively;
(c) a valve spool positioned in said first bore so as to divide said first bore into first and second ends, said valve spool having an internal bore formed therein adjacent to said second end of said first bore, a stop connected to the inner periphery of said internal bore, an annular groove which is in constant communication with said inlet passage and with at least one of said outlet passages, and a passageway formed therein having a first opening which is in constant communication with said first end of said first bore and a second opening which is in constant communication with said first outlet passage, said valve spool being movable between a first position wherein said annular groove is in communication with said first outlet passage, while simultaneously sealing said second outlet passage from communication with said annular groove, and a second position wherein said annular groove is in communication with said second outlet passage, while simultaneously sealing said first outlet passage from communication with said annular groove;
(d) a pin movably positioned in said second bore having first and second enlarged ends, said first enlarged end extending into said internal bore formed in said valve spool beyond said stop and said second enlarged end extending into said spring cavity, said enlarged ends limiting the movement of said pin with said first enlarged end being sized to engage said stop after movement of said pin for a predetermined distance out of said internal bore;
(e) a first spring positioned in said first bore between said valve spool and said first enlarged end of said pin for urging said valve spool toward said first position;
(f) a second spring positioned in said spring cavity which contacts said second enlarged end of said pin for urging said pin into said first bore;
and
(g) a load signal passage establishing fluid communication between said priority function and said second end of said first bore which fluid acts to urge said valve spool toward said first position and said pin out of said bore such that a decrease in pressure difference between said load signal passage and said inlet passage urges said valve spool to move toward said first position, an increase in pressure difference between said load signal passage and said inlet passage allows said valve spool to move toward said second position, and a predetermined maximum fluid pressure within said load signal passage causes said first enlarged end of said pin to contact said stop and force said valve spool toward said second position.

5 more elements

Dependencies are inferred from the claim text.