US3838570A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Directional control valve
Assignee: Parker Hannifin Corp
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Filing: 1973-09-10
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Granted: 1974-10-01
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Expires: 1993-09-10
Abstract
Abstract A directional control valve especially adapted for use as a steering control valve in the power steering circuit of mobile equipment such as a fork lift truck characterized in that valve housing has a valve member movable therein to determine the direction of actuation of the steering cylinder and to determine the speed of actuation of the steering cylinder by defining with the valve housing a variable area meter-out orifice in the return path of fluid flow from the steering cylinder. The valve herein is further characterized in that the housing is formed with two inlet ports, one for connection with a variable displacement pump, and the other for connection with a fixed displacement pump, the arrangement being such that in the event of failure of the variable displacement pump, the steering system may be operated by the fixed displacement pump, the valve housing containing an unloading valve which senses pressure upstream of the meter-out orifice to bypass the excess flow from the fixed displacement pump over and above that flow required to satisfy the demand set by the directional control valve member at the aforesaid variable area meter-out orifice. In the case of the variable displacement pump, the valve housing is provided with a sensing port to sense the pressure drop across the variable area meter-out orifice thereby to adjust the variable displacement pump to supply fluid at a rate as set by the variable area meterout orifice for actuating the steering cylinder at desired selected speed.
Inventors
- 👤 W Marietta
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 11:35
CPC Classifications
F; F15; F15B; F15B11/00; F15B11/16; F15B11/17; F15B13/00; F15B13/02; F15B13/04; F15B13/0416; F15B13/0417; F15B2211/00; F15B2211/20; F15B2211/205; F15B2211/2053; F15B2211/20538; F15B2211/20546; F15B2211/20553; F15B2211/20576; F15B2211/30; F15B2211/305; F15B2211/30505; F15B2211/31; F15B2211/3105; F15B2211/3111; F15B2211/315; F15B2211/3157; F15B2211/31582; F15B2211/40; F15B2211/405; F15B2211/40515; F15B2211/455; F15B2211/60; F15B2211/605; F15B2211/6051; F15B2211/70; F15B2211/75
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
264 words
A directional control valve comprising a housing having a bore intersected axially therealong by an inlet passage and by pairs of cylinder, sensing, and return passages, said passages being respectively adapted for connection with both a variable displacement pump and a fixed displacement pump via check valves upstream of said bore, with a double acting power steering cylinder, with both a controller for said variable displacement pump and an unloader for said fixed displacement pump, and with a tank; a valve spool movable in said bore from a neutral position blocking communication between said inlet and cylinder passages and between said sensing and return passages to either of two operating positions communicating said inlet passage with one of said cylinder passages and communicating the other one of said cylinder passages with a return passage via a sensing passage and a variable area orifice between said sensing and return passages of size according to the extent of movement of said spool to either of said operating positions; said directional control valve having a bleed orifice communicating said inlet passage with said sensing passage; and a spring biased unloading valve member in said housing exposed to fluid pressure in said sensing and return passages and being movable by predetermined pressure drop across said variable area metering orifice to bypass excess flow from said fixed displacement pump to said return passage; said inlet passage being normally supplied with fluid under pressure from said variable displacement pump but in the event of failure thereof, fluid under pressure is supplied to said inlet passage by said fixed displacement pump.
Claim 2
Dependent Claim
264 words
A directional control valve comprising a housing having a bore intersected axially therealong by an inlet passage and by pairs of cylinder, sensing, and return passages, said passages being respectively adapted for connection with both a variable displacement pump and a fixed displacement pump via check valves upstream of said bore, with a double acting power steering cylinder, with both a controller for said variable displacement pump and an unloader for said fixed displacement pump, and with a tank; a valve spool movable in said bore from a neutral position blocking communication between said inlet and cylinder passages and between said sensing and return passages to either of two operating positions communicating said inlet passage with one of said cylinder passages and communicating the other one of said cylinder passages with a return passage via a sensing passage and a variable area orifice between said sensing and return passages of size according to the extent of movement of said spool to either of said operating positions; said directional control valve having a bleed orifice communicating said inlet passage with said sensing passage; and a spring biased unloading valve member in said housing exposed to fluid pressure in said sensing and return passages and being movable by predetermined pressure drop across said variable area metering orifice to bypass excess flow from said fixed displacement pump to said return passage; said inlet passage being normally supplied with fluid under pressure from said variable displacement pump but in the event of failure thereof, fluid under pressure is supplied to said inlet passage by said fixed displacement pump.
Claim 3
Dependent Claim
87 words
The directional control valve of claim 1 wherein said pairs of cylinder, sensing, and return passages respectively straddle said inlet passage and each other; and wherein said spool has lands thereon which in the neutral position of the spool block both cylinder passages and has metering lands thereon which in the neutral position of said spool block communication between adjacent sensing and return passages and which in either of said operating positions of said spool establish said variable area metering orifice between adjacent sensing and return passages.
Claim 4
Dependent Claim
30 words
The directional control valve of claim 1 wherein said bleed orifice is contained in said spool and is closed when Said spool is moved to either of its operating positions.
Claim 5
Dependent Claim
55 words
The directional control valve of claim 1 wherein said housing has an unloading valve bore in which said unloading valve member is movable, said unloading valve bore being intersected by said sensing passage, by one of said return passages, and by the inlet passage from said fixed displacement pump upstream of said check valve therein.
Claim 6
Dependent Claim
175 words
A directional control valve for a power steering cylinder comprising a housing having a bore intersected axially therealong by inlet, cylinder, sensing, and return passages respectively adapted for connection with a pump, a power steering cylinder, a pump control means, and a tank; a valve spool movable in said bore from a neutral position to an operating position to control fluid flow from said inlet passage to one of said cylinder passages and from the other of said cylinder passages to said return passage via a variable area metering orifice between said sensing and return passages of size according to the extent of movement of said spool to said operating position; said spool having bleed orifice means communicating said inlet and sensing passages with each other, said bleed orifice being closed upon movement of said spool from neutral position to operating position whereby the flow through said variable area metering orifice comprises only the flow of fluid from said other cylinder passage to said return passage via said sensing passage and variable area metering orifice.
Claim 7
Dependent Claim
175 words
A directional control valve for a power steering cylinder comprising a housing having a bore intersected axially therealong by inlet, cylinder, sensing, and return passages respectively adapted for connection with a pump, a power steering cylinder, a pump control means, and a tank; a valve spool movable in said bore from a neutral position to an operating position to control fluid flow from said inlet passage to one of said cylinder passages and from the other of said cylinder passages to said return passage via a variable area metering orifice between said sensing and return passages of size according to the extent of movement of said spool to said operating position; said spool having bleed orifice means communicating said inlet and sensing passages with each other, said bleed orifice being closed upon movement of said spool from neutral position to operating position whereby the flow through said variable area metering orifice comprises only the flow of fluid from said other cylinder passage to said return passage via said sensing passage and variable area metering orifice.
Claim 8
Dependent Claim
69 words
The directional control valve of claim 5 wherein said pump control means comprises a spring biased unloading valve member in a bore in said housing exposed to fluid pressure in said sensing passage and in said return passage and movable in said bore to bypass excess flow from said inlet passage to said return passage when the pressure drop across said variable area metering orifice exceeds a predetermined value.
Claim 9
Dependent Claim
47 words
The directional control valve of claim 5 wherein said pump control means comprises the controller of a variable displacement pump which is exposed to fluid pressure in said sensing passge and in said return passage to maintain a predetermined pressure drop across said variable area metering orifice.
References Cited (Backward Citations)
US3747725A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-09-30 | 1978-04-01 | 1978-10-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-09-30 | 1982-04-01 | 1982-10-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-09-30 | 1986-04-01 | 1986-10-01 | $7700.00 | Window Closed / Lapsed |