EP0064497A1 - Vanne de commande d'ecoulement sensible a la charge - Google Patents

Vanne de commande d'ecoulement sensible a la charge

Info

Publication number
EP0064497A1
EP0064497A1 EP19810901372 EP81901372A EP0064497A1 EP 0064497 A1 EP0064497 A1 EP 0064497A1 EP 19810901372 EP19810901372 EP 19810901372 EP 81901372 A EP81901372 A EP 81901372A EP 0064497 A1 EP0064497 A1 EP 0064497A1
Authority
EP
European Patent Office
Prior art keywords
bore
control valve
flow control
passage
fluid
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP19810901372
Other languages
German (de)
English (en)
Inventor
Jerry L. Reeves
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Caterpillar Industrial Inc
Original Assignee
Towmotor Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Towmotor Corp filed Critical Towmotor Corp
Publication of EP0064497A1 publication Critical patent/EP0064497A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B66—HOISTING; LIFTING; HAULING
    • B66F—HOISTING, LIFTING, HAULING OR PUSHING, NOT OTHERWISE PROVIDED FOR, e.g. DEVICES WHICH APPLY A LIFTING OR PUSHING FORCE DIRECTLY TO THE SURFACE OF A LOAD
    • B66F9/00—Devices for lifting or lowering bulky or heavy goods for loading or unloading purposes
    • B66F9/06—Devices for lifting or lowering bulky or heavy goods for loading or unloading purposes movable, with their loads, on wheels or the like, e.g. fork-lift trucks
    • B66F9/075—Constructional features or details
    • B66F9/20—Means for actuating or controlling masts, platforms, or forks
    • B66F9/22—Hydraulic devices or systems
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B13/00—Details of servomotor systems ; Valves for servomotor systems
    • F15B13/02—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors

Definitions

  • This invention relates to a flow control valve for a fluid operated system and more particularly to a load responsive flow control valve for a fluid operated lift system which establishes a flow rate in response to a load being lifted prior to the initiation of fluid flow.
  • Flow control valves are frequently used in fluid operated systems, such as a lift system.
  • fluid operated systems such as a lift system.
  • such valves when used with a lift mast on a lift truck such valves permit substantially unrestricted fluid flow to be delivered from a pump to a fluid operated motor, such as a hydraulic jack', and controllably regulate the rate of flow passing from the jack to a reservoir.
  • Such systems include a main control valve for controllably directing the fluid flow between the jack, pump and reservoir. Actuation of the main control valve and passing fluid flow to tank establishes a d i f f e renti al pressure condition upon which the flow control valve reacts for establishing a rate of flow proportional to said differential pressure.
  • a fluid operated system is shown in U.S. Patents 4,180,098, issued December 25, 1S79 to T. Budzich and U.S. Patent 4,204,459, issued May 27, 1980 to H.L. Johnson. It has been found that flow control valves, operative in response to a d i fferenti al pressure established subsequent to the initiation of fluid flow, have a tendency to either react too slowly or too quickly in achieving a flow regulating position.
  • a slow reacting flow control valve will tend to reduce the responsiveness of the system and thus the controllability and efficiency will suffer.
  • a fast reacting flow control valve will have a tendency to overshoot and hunt resulting in erratic or cyclical control of the flow and bouncing of the hydraulic jack
  • the present invention is directed to overcoming one or more of the problems as set forth above.
  • a flow control valve for a fluid operated system having a motor.
  • the flow control valve includes a housing having a bore and a passage in the housing opening in the bore and connected to the motor.
  • a piston arc a plunger are each slidably disposed in the bore and seperable to a nonmodulating position with respect to the passage permitting substantially unrestricted fluid flow to the motor and being movable together to a flow modulating position with respect to said passage in response to the fluid pressure in the motor.
  • the flow control valve Simultaneously with the termination of fluid flow through the passage to the motor the flow control valve automatically esta bl i shes a maximum rate of fluid flow from the motor prior to the initiation of fluid flow from the motor through the passage.
  • FIG. 1 is a schematic diagram of the fluid operated system including the flow control valve of the present invention.
  • Fig. 2 is an enlarged d i ag ramma t i c sectional view of the flow control valve of Fig. 1 shewing the plunger and piston in a nonmodulating position.
  • Fig. 3 is an enlarged diagrammatic sectional view of the flow control valve of Fig. 1 shewing the plunger and piston together in abutment in a flow modulating position.
  • Fig. 4 is an enlarged diagrammatic view of the passage as seen in the direction of the arrows IV-IV of Fig. 3.
  • a fl ui d operated system 10 such as a hydraulic lift system for use on a material handling vehicle (not shown) includes a source of pressurized fluid 12, such as a pump, a control valve 14, a fluid operated motor 16, such as a single acting hydraulic jack, a flov; control valve 18 and a reservoir 20.
  • the pump 12 is connected to the control valve 14 by a conduit 22 and to the reservoir 20 by a conduit 24.
  • the control valve 14, a manually actuated three position open center type control valve is connected to the reservoir 20 by a conduit 26 and to flov/ control valve 15 by a conduit 28.
  • Flow control valve 18 is preferably connected to jack 16 directly so as to pass fluid flow betweeen the jack 16 and control valve 14.
  • the flow control valve 18 could be connected directly to the control valve 14 or anywhere between the control valve and jack 16 and to the conduit 28.
  • the flow control valve 18 includes a housing 30 having a first cylindrical end portion 32 and a surface 33, a second cylindrical end portion 34 and a flange portion 36 extending radially from the first end portion 32 adjacent the second end portion 34 and dividing the first and second end portions.
  • Each of the first and second end portions 32,34 have a threaded portion 38 extending radially therefrom and along a preselected axial distance.
  • the jack 16 as shown in Fig. 1, has a tubular cylinder 40 and a piston and rod assembly 42 slidably disposed in the cylinder and extendable and retractable relative thereto. Adjacent a head end of the cylinder is provided a threaded bore 44 opening into a cavity 46 therein. The cavity 46 is open to and in fluid communication with a head end 48 of the piston and rod assembly 42.
  • the housing 30, and more specifically its first end portion 32, is disposed in the cavity 46 with the threaded portion 38 of the first end portion engaged in the threaded bore 44 of the cylinder 40.
  • a drilled passage 54 is disposed in the housing and is open at a second end 56 of the housing and extends toward the first end portion 52 of the housing 30 a preselected depth.
  • a passage 58 is disposed in the housing's second end portion 32 at a preselected axial location along the second end portion of the housing, preferably between the threaded portion 38 and the first end 52.
  • the passage 58 is preferably radially oriented relative to e bore 50 and the first cylindrical end portion 32 and passes through the housing to a depth so as to open in the bore 50 and the drilled passage 54.
  • the drilled passage 54, the bore 50 and the passage 58 together pass fluid between conduit 28 and cavi ty 46 (see Fig. 1).
  • a blind stepped bore 60 having a seal support bore portion 62 and a guide bore portion 64 is disposed in the housing 30 in axial alignment with the bore 50.
  • the seal support portion 62 is smaller in diameter than the bore 50 and the guide bore portion 64 is smaller in diameter than the seal support bore portion 62.
  • the seal support portion is connected to the second end of the bore 50 and opens in the bore 50.
  • a vent passage 66 is radially disposed in the flange 36 to connect the guide bore portion 64 to the atmosphere so as to prevent fluid pressure buildup therein.
  • a filter 68 of any suitable type well known in the art is positioned in the vent passage to prevent dirt from entering the guide bore portion.
  • a flow control piston 70 is slidably disposed in said bore 50 adjacent the first end 51 of the bore.
  • the piston 70 has a cylindrical body 72, a head surface 74, a base end 76 and a cylindrical recess 78 disposed in said base end and into said body 72.
  • a first spring 80 is disposed in the recess 78 and bears against a flange 82 retained in said bore 50 in any suitable manner, such as by a snap ring 84, to bias the piston 70 toward the second end. 53 of the bore.
  • a stop or plunger 86 is slidably disposed in the bore 50 adjacent the second end 53 thereof.
  • the plunger 86 includes a cylindrical head portion 88 which has a stop surface 90 and a connecting surface 92, and a cylindrical shank portion 94 which is rigidly centrally affixed to extend axially from the connecting surface 92.
  • a second spring 96 is centrally disposed about shank 86 and between the connecting surface 92 and the second end 53 of the bore 50.
  • the second spring 96 biases the plunger toward the first end 51 of the bore by applying force to the connecting surface 92 and a flange 98 retained at the second end 53 of the bore 50.
  • a seal ICO is disposed in seal support bore 62 and in sealing engagement with the support bore 62 and the shank portion 94 of the plunger S6.
  • the seal 100 prevents pressurized fluid from entering the guide bore 64 and acting against a crossectional area of the shank 86.
  • the piston 70 and plunger 86, flow control members, are axially movable in the bore in response to fluid pressure applied thereto or in the absence of pressure to a spring biased axial position in the bore 50. In both situations the position of the plunger 70 and the piston are significant.
  • the piston 70 cooperates with the passage 58 to regulate the flow of fluid therethrough and the plunger establishes a position in the bore at which to stop the piston from further movement in the direction toward the piston thereby establishing a maximum flow rate for a given pressure.
  • the head portion 88 of the plunger 86 was designed with a very thin crossectional area between the stop surface 90 and the connecting surface 92 to eliminate or reduce the possibility of the plunger 86 affecting flow of fluid through the passage 58.
  • the piston functions as a flow modulating member within the passage 58.
  • the preferred passage 58 configuration has a basic keyhole shape oriented axially along the first cylindrical end portion 32 of surface 33.
  • the passage is disposed radially in the housing 30, relative to the bore 50, and opens on surface 33, and in bore 50 and drilled passage 54, as previously discussed.
  • the keyhole shaped passage 58 has a circular end portion 102 and a rectangular end portion 104 extending from said circular end portion. The circular end portion 102 is postioned closer to the first end portion 52 of the housing 30 than the rectangular end portion 104.
  • the rectangular end portion 104 preferably terminates with an arcuate end portion 106. It is to be noted that the rectangular portion 104 between the bore 50 and the drilled passage 54 is preferably shorter axial length than the rectangular portion 104 between the bore 50 and the surface 33 of the first cylindrical end portion 32. This establishes a slight pressure drop with fluid flowing across the passage portion between the bore 50 and drilled passage 54 and not with the passage portion between the outer surface 33 and the bore 50, thereby improving the flow modulating characteristics.
  • the piston 70 is axially movable in the bore 50 between a nonmodulating postion, as shown in Fig. 1 at which time it is in abutment with the flange 82 at the first end 51 of the bore 50 and spaced away from an overlying postion with the passage 58 to a flow modulating position wherein the piston moves toward the second end 53 to lie within the passage 58.
  • a flow modulating position wherein the piston moves toward the second end 53 to lie within the passage 58.
  • One of such positions is shown in Fig. 3.
  • the large circular passage portion 102 is provided primarily to permit free unrestricted flow when the piston 70 is in the nonmodulating position and is sized according to the flow capacity of the system 10.
  • Both the piston 70 and the plunger 86 are continuously automatically responsive to the fluid pressure in the cavity 46 of jack 16. This pressure generates a force proportional to the weight of a load being supported by the piston and rod assembly 42 and is commonly termed load pressure.
  • load pressure The presence of load pressure in the cavity 46 will cause the plunger 86 to seek a pressure force balanced position in the bore 50 since the passage 58 and the entire bore 50 are in continuous open communication with the fluid in the cavity 46.
  • the load pressure acts against the stop surface 90 and the connecting surface 92 of the head portion 82 of the plunger 86 to cause the plunger to move to a pressure force balanced axial postion in the bore 50.
  • the axial force balanced position is determined by the differential area established on the stop surface 90 and the opposing force of second spring 96.
  • the differential area is the surface area of the stop surface 90 minus the surface area of the connecting surface 92 less the crossectional area of the shank portion 94.
  • the flow control piston 70 like the plunger 86 is responsive to load pressure.
  • the load pressure acts against the head surface 74 and the base end 76 including the cavity 78. Since the effective area of the head surface 74 and the base end 76 plus the cavity 78 are equal, the first spring 80 will force the piston 70 to move into abutment with the stop surface 90 of plunger 86. This is true in all conditions except one such as shown in Fig. 2.
  • the pressurized fluid flow from bore 50 across passage 58 encounters a slight pressure drop across the passage.
  • the plunger 86 will, at the same time, automatically seek the forced balanced position in the bore 50 in response to the fluid pressure. However, due to its construction it will have substantially no effect on the flow being delivered to cavity 46. The force of the fluid pressure acting against the head end 48 of the piston and rod assembly 42 will cause extension thereof and the lifting of a load (not shown).
  • the load pressure acting against the head surface 74 and the base end 74 of the piston 70 are equal. Since no differential area is present the piston 70 will automatically move into abutment with the plunger 86 as shown in Fig. 3 under the influence of first spring 80 and establish a flow rate with the passage 58 as determined by the position of plunger 86, Thus, it can be seen, that the position of the plunger 86 in the bore 50 is directly proportional to the weight of the load being lifted. For heavy loads, the plunger will be at a position closer to the second end 53 of the bore than for light loads o r no l oad .
  • a flow control valve for a fluid operated system which is continuously responsive to fluid pressure in the motor to establish a flow rate in response to this pressure prior to the initiation of flow of any fluid from the motor and affording substantially unrestricted fluid flow in the opposite direction to the motor.

Landscapes

  • Engineering & Computer Science (AREA)
  • Structural Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Transportation (AREA)
  • Fluid Mechanics (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Civil Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Geology (AREA)
  • Fluid-Pressure Circuits (AREA)

Abstract

Vanne (18) de commande d'ecoulement pour un systeme (10) actionne par un fluide pourvu d'un moteur (16). La vanne de commande d'ecoulement (18) possede un alesage (50) et un passage (58) debouchant dans l'alesage. Un piston (70) et un plongeur (86) sont disposes de maniere coulissante dans l'alesage (50). Le plongeur (86) peut etre actionne en reponse a une pression de charge dans le moteur (16) de maniere a etablir une position axiale dans l'alesage (50) a laquelle le piston (70) regle l'ecoulement du fluide a l'interieur du passage, avant l'introduction du fluide au travers de la vanne depuis le moteur (16). La vanne de commande d'ecoulement permet ainsi d'ameliorer la reponse et le reglage et requiert un nombre inferieur de pieces moins complexes. La vanne de commande d'ecoulement (18) est particulierement utile dans un systeme hydraulique de levage du type utilise dans un chariot de levage.
EP19810901372 1980-11-10 1980-11-10 Vanne de commande d'ecoulement sensible a la charge Withdrawn EP0064497A1 (fr)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/US1980/001510 WO1982001748A1 (fr) 1980-11-10 1980-11-10 Vanne de commande d'ecoulement sensible a la charge

Publications (1)

Publication Number Publication Date
EP0064497A1 true EP0064497A1 (fr) 1982-11-17

Family

ID=22154646

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19810901372 Withdrawn EP0064497A1 (fr) 1980-11-10 1980-11-10 Vanne de commande d'ecoulement sensible a la charge

Country Status (3)

Country Link
EP (1) EP0064497A1 (fr)
JP (1) JPS57501741A (fr)
WO (1) WO1982001748A1 (fr)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104495709B (zh) * 2015-01-20 2016-11-30 宁波高新协力机电液有限公司 用于电动叉车上的负载压力反馈比例多路阀
IT201900007212A1 (it) * 2019-05-24 2020-11-24 L T E Lift Truck Equipment S P A Carrello elevatore.

Family Cites Families (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2603235A (en) * 1952-07-15 Kirkham
US2495785A (en) * 1945-01-11 1950-01-31 Hydraulic Equipment Company Lowering valve
US3016046A (en) * 1960-05-05 1962-01-09 Clark Equipment Co Regulator valve
US3072107A (en) * 1961-03-16 1963-01-08 Flowmatic Controls Inc Hydraulic lift control system and valve therefor
US3420146A (en) * 1966-10-28 1969-01-07 Eaton Yale & Towne Lowering valve
US3583431A (en) * 1969-02-17 1971-06-08 Cessna Aircraft Co Pressure relief valve
US4022113A (en) * 1975-12-10 1977-05-10 Blatt Leland F Flow control valve
US4180098A (en) * 1976-02-05 1979-12-25 Tadeusz Budzich Load responsive fluid control valve
US4204459A (en) * 1978-04-19 1980-05-27 Caterpillar Tractor Co. Combination check and flow control valve for hydraulic systems

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO8201748A1 *

Also Published As

Publication number Publication date
JPS57501741A (fr) 1982-09-24
WO1982001748A1 (fr) 1982-05-27

Similar Documents

Publication Publication Date Title
US4244275A (en) Counterbalance valve
US4206688A (en) Overrunning load control for hydraulic motors
US3964262A (en) Hydrostatic transmission control system
US4111283A (en) Regulator valve
US3595343A (en) Control system for lift trucks
US4338856A (en) Dual pilot counterbalance valve
EP0087213B1 (fr) Camion à cabine basculante ayant un mouvement à vide hydraulique
US4509406A (en) Pressure reducing valve for dead engine lowering
KR910007287B1 (ko) 유량 제어 기구를 구비한 방향 제어 밸브
US4466336A (en) Control valve for hydraulic motor apparatus
US4779416A (en) Control system for front end loader boom and bucket operating systems
GB1598487A (en) Control valves for fluid pumps
US4028890A (en) Piston pump assembly utilizing load pressure control
US4165675A (en) Load check valve cylinder mounted
US4930975A (en) Control for load carrier for industrial vehicle
EP0064497A1 (fr) Vanne de commande d'ecoulement sensible a la charge
US4620560A (en) Modulating relief valve with dual functioning load piston
GB1431641A (en) Valve mechanism
US3782249A (en) Hydraulic control system with locking valve to prevent accidental or unauthorized lowering of a tractor implement
US4727793A (en) Signal valve for pressure compensated system
US4085920A (en) Pilot control valve with servo means
US3890788A (en) Hydrostatic drive system
US4398869A (en) Control means for variable displacement pump
US4404891A (en) Brake valve for a hydraulically powered winch
US3612088A (en) Throttling draft control valve

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

17P Request for examination filed

Effective date: 19820331

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): AT CH DE FR GB LI NL SE

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE APPLICATION HAS BEEN WITHDRAWN

18W Application withdrawn

Withdrawal date: 19821105

RIN1 Information on inventor provided before grant (corrected)

Inventor name: REEVES, JERRY L.