Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
  • F16D48/00—External control of clutches
  • F16D48/02—Control by fluid pressure
  • F16D48/04—Control by fluid pressure providing power assistance
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
  • F16D25/00—Fluid-actuated clutches
  • F16D25/12—Details not specific to one of the before-mentioned types
  • F16D25/14—Fluid pressure control
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
  • F16D48/00—External control of clutches
  • F16D48/02—Control by fluid pressure
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
  • F16D48/00—External control of clutches
  • F16D48/02—Control by fluid pressure
  • F16D2048/0209—Control by fluid pressure characterised by fluid valves having control pistons, e.g. spools

Definitions

• the invention relates to a hydraulic circuit which controllably provides first and second preselected fluid pressure levels in the circuit to operate associ ⁇ ated elements each requiring one of the pressure levels- More particularly, the invention relates to a hydraulic valve to automatically provide a first pressure level condition for operation of only a first means and con ⁇ trollably provide both first and second pressure level conditions for subsequent operation of a second means and the first means.
• the present invention is directed to over ⁇ coming one or more of the problems as set forth above.
• a hydraulic circuit has fluid supply means for delivering a pressurized fluid flow and , first and second means operating at first and second preselected pressure levels, respectively.
• a main valve element has an inlet annulus positioned in fluid communication with the fluid supply means. The valve element is movable between a first position at which the inlet annulus is blocked from fluid communication with the first means and a second position at which the inlet annulus is in fluid communication with both the first and second means.
• Pilot means automatically communicates the inlet annulus with the first means at the first position of the valve element and initiates a condition demanding pressurized fluid flow at about the first preselected pressure level in response to a reduced fluid flow from the supply means.
• the pilot means also controllably initiate a condition demanding pressurized fluid flow at about the second preselected pressure level in response to a preselected input signal.
• a hydraulic circuit has fluid supply means for delivering a pressurized fluid flow and first and second fluid pathways which operate at first and second preselected fluid pressure levels, respectively.
• Means is provided for selectively, controllably irecting fluid flow from the fluid supply means through the first and second fluid pathways.
• the means is movable toward a first position at which fluid flow is delivered through the first fluid pathway at about the first preselected pressure level in response to a reduced fluid flow and movable toward a second position at which fluid flow is delivered at about the first and second preselected pressure levels through the first and second fluid pathways, respectively, in response to a preselected input signal.
• a valve has main valve and pilot valve elements.
• the main valve element has a spool movable in a bore between first and second positions. At the first posi ⁇ tion, an inlet annulus of the valve element is blocked from communication with an outlet annulus of the valve element. At the second position, the inlet annulus is positioned in communication with the outlet annulus.
• First biasing means is provided for urging the spool toward its first position.
• a pilot valve element also has a spool movable in a bore between a first position at which a second supply annulus of the pilot valve element is positioned in communication with a third annulus of the pilot valve element and blocked from communication with a first annulus of pilot valve element and a second position at which the second annulus is in communication with the first annulus and blocked from communication with the third annulus.
• the above-described hydraulic circuits and valve can be used to, for example, assist starting of an engine by unloading an associated clutch.
• the clutch can be automatically unloaded after engine shut-down by reducing hydraulic fluid pressure to the clutch to below its actuation or engagement pressure. This maintains the engine at an unloaded condition for the next start ⁇ up while maintaining fluid flow to other hydraulic circuits. Following starting and a warm-up period the necessary actuation pressure can be initiated to the clutch by a signal from the operator ' . ⁇ «
• Fig. 1 is a diagrammatic view of one embodi ⁇ ment of the present invention; shown as a valve in partial cross section and at a first operating position, associated with a lubrication system and clutch of an engine; and
• Fig. 2 is a diagrammatic view of the valve similar to Fig. 1 shown in a second operating position.
• a hydraulic circuit 10 which includes a fluid supply means or supply pump 12 for deliverying a pressurized fluid flow, a valve 14 and first and second means 16,18 which operate at first and second preselected fluid pressure levels, respectively.
• the first means 16 represents a work element such as the pump drive bearings 20 of a main hydraulic pump associated with an engine of a work vehicle (not shown) .
• the drive bearings are connected to the supply pump through the valve by, a first fluid pathway 24.
• the second means 18 similarly is repre ⁇ sented by a work element such as a clutch 26 which has, and is connected to the pump through the valve by, a second fluid pathway 28.
• Fluid delivered from the pump during operation of the engine will therefore be de ⁇ livered through the valve to the clutch and pump drive bearings.
• the first fluid pathway 24 from the pump 12 maintains or creates a particular or first preselected resistance to fluid flow at the pump which determines the pressure level at which fluid is delivered from the pump and through the pathway to lubricate the engine.
• the first preselected pressure level related to the first preselected resistance is established by the configuration of the pathway through which the fluid flows.
• the second fluid pathway 28 determines a second preselected fluid pres- sure level relative to a second preselected resistance to fluid flow which, in this instance, is characterized by the actuation pressure at which the clutch becomes engaged in response to the set fluid pressure level.
• the valve controls the fluid pressure levels in the hydraulic circuit, as will be discussed hereinafter, to lubricate the pump drive bearings and provide engagement pressure to the clutch when desired.
• valve 14 essentially represents means movable between first and second posi- tions for selectively, controllably directing fluid flow from the pump 12 through the first and second fluid pathways 24,28. At the first position of the means
• the first fluid pathway is in fluid communica- tion with the pump 12 and fluid flow is delivered at
• said valve consists of a pressure regulating valve means or main valve element 30 and pilot means 32, such as a pilot valve element 34.
• the main valve element is a modulating spool valve assembly which has an inlet annulus 36, an outlet annulus 38 and a spool 40.
• the spool has a groove 42 and is movable in a bore 44 of the valve element.
• the pilot valve element includes first, second and third fluid supply annuli 46,48,50 and is positioned in fluid communication with the inlet annulus through its second annulus and with the outlet annulus through its third annulus.
• each of the valve ele ⁇ ments is movable between respective, related first (shov/n in Fig. 1) and second (shown in Fig. 2) positions to determine the pressure level of the fluid flow from the pump 12 to the lubrication system 20 and the clutch 26.
• the inlet annulus 36 of the main valve element 30 is in communication with the pump 12 and the clutch 26 through and as a portion of the second fluid pathway 28. Passageways 52,54 in the valve 14 also represent a portion of the second fluid pathway.
• the outlet annulus 38 connects the main valve element to the pump drive bearings 20 by being positioned in communication with said system. The outlet annulus 38 also forms a portion of the first fluid pathway as does another passage 56 in the valve and the passage 52.
• the main valve element 30 has a load piston 58 and biasing means 60 for urging the spool 40 toward a first position 62 which corresponds with the first position of the main valve element.
• pilot pressure means 61 is provided for urging the main valve element towards its second position.6.3 and against the biasing means.
• the biasing means 60 is shown as a spring 64 located between the load piston and the spool in the bore 44.
• the pilot pressure means is a- first pilot chamber 66.
• the first pilot chamber 66 and a second pilot chamber 68, defined in the bore and by the spool and load piston, respectively, are associated with first and second ends 70,72 of the spool, respec ⁇ tively.
• reaction slug 74 and check valve 76 are positioned in the first pilot chamber which is in fluid communication with the inlet annulus 36 through pas ⁇ sageways 77,79 in the valve. It will be readily seen that movement of the spool depends upon the fluid pressure level in the pilot chambers which will work against the spring tending to move the spool or alter the effective rate of the spring.
• the pilot valve element 34 has a spool 78 consisting of first and second lands 30,82 intercon ⁇ nected to a stem 84.
• the spool is movable in the bore between first and second positions 86,88 which correspond to the first and second positions of the pilot valve element.
• the spool portions are spaced one from the other to define a moving work chamber 90' (Fig. 1) , 90" (Fig. 2) within a bore 91 of the element.
• the second supply groove 48 of the pilot valve element is in communication with the third groove 50 and blocked from communication with the first supply groove 46 to define the work chamber 90' of Fig. 1.
• the second supply groove is in communication with the first supply groove and blocked from communication with the third supply groove to define the work chamber 90" of Fig. 2.
• bleed means 92 is provided for automatically, controllably reducing or relieving the fluid pressure level in the work chamber, and thus the second fluid pathway 28.
• the bleed means is shown as a notch' 94 of predetermined configuration on the first land which meters the fluid from the work chamber across the first land and through a drain passageway 98 to tank 100.
• said valve is provided with biasing means 102 for continuously urging the pilot valve element toward its first position (Fig. 1) and pilot pressure means 104 for controllably urging the pilot valve element against said biasing means and toward its second position.
• the biasing means is a spring 106 acting against the stem 84 adjacent the first land 80 of the pilot valve element.
• the pilot pressure means is a chamber 110 defined by the bore 91 and the second land 82 and positioned in communication with the first supply annulus 46 and the second pilot chamber 68 through a passageway 112 in the valve 14.
• An orifice 114 meters fluid entry from the pilot valve element into the second pilot chamber.
• a solenoid 116 preferably
• the valve 14 automatically positions itself in order to disengage the hydraulically operated clutch 26 when the associated engine is shut-down for releasing the load on the engine caused by the engaged clutch. Therefore, when starting is next attempted the engine will be free from the clutch load and easier to turn-over.
• the valve also maintains fluid flow to the main hydraulic pump drive bearings so that upon start-up fluid is immedi ⁇ ately pumped thereto for lubrication purposes.
• the spools 40,78 are in their first positions 62,86 which correspond to the first positions of their related main and pilot valve elements 30,34.
• the inlet annulus 36 is positioned in fluid communication with the pump drive 20 through the pilot valve element.
• pressurized fluid will flow from the pump 12 and through the main valve element and the pilot valve element and back to the main valve element by way of passageways 118,120 interconnecting the main and pilot valve elements.
• the inlet annulus 36 of the main valve element is also positioned in fluid communication with the clutch at the 'first position of Fig. 1 and fluid will pass through the passageway 54 to the clutch.
• the pressure level at which fluid flows from the pump 12 at start-up is the . first preselected pres ⁇ sure level, as established by- the first fluid pathway 24 and, in part, by the pathway through the valve, owing to the associated first preselected resistance being less than the second preselected resistance established in the circuit 10 by the clutch. In the embodiment shown, this is particularly evident owing to the significant differences on pressure levels at which a lubrication system and clutch, typically 20-50 psi and 200 psi, respectively, operate.
• the hydraulic circuit 10 remains in the fluid flow configuration of Fig. 1 absent an external signal. Following successful starting of the engine 22 and a warm-up period if desired, the operator delivers such an input signal to the pilot valve element 34 by moving a rod 122 of the solenoid 116 against the pilot valve element stem 84. This can be done manually or electrically.
• the pilot valve element is thereby moved to its second position, shown in Fig. 2, in response to the preselected signal for controllably initiating a condition ' in the circuit 10 demanding fluid flow at about the second preselected pressure level.
• the pilot valve element is signalled to alter the hydraulic circuit, as will be further explained, to make the pump work against the higher second preselected resistance to fluid flow. against the higher resistance, the pump will deliver fluid at the higher second fluid pressure level to activate the clutch.
• the solenoid rod and biasing means such as springs (not shown) , will return it to its neutral or disengaged position.
• the main valve element 30 is moved to its second position as the fluid pressure acts against the _ slug 74 in the first pilot chamber 66 to move the spool 40 toward its second position in Fig. 2. However, pressure will also build toward the second pressure level in the first pilot chamber 68 tending to move the load piston 58 against a stop 124 on the bore.
• the load piston movement upstages the force of the spring 64 which works against a similar pressure build-up in the first pilot chamber to move the pressure level to second preselected pressure level.
• the supply annulus 42 is opened into communication with the outlet annulus 38 and provides sufficient fluid at the second pressure level to actuate the clutch 26 and to provide lubricating fluid to the engine 22 at the first preselected pressure level.
• the spool will move back toward its first position shutting off the pathway through the supply annulus.
• the main valve element is then movable from its second toward its first position of Fig. 1 in response to the reduced fluid flow at the lower pressure level.
• the clutch is deactivated and the pilot valve is movable from its second toward its first position of Fig. 1 owing to the biasing action of the spring 106.
• the main valve element 30 then moves to its first position at the first position of the pilot valve element 34 and a condition is initiated in the circuit 10 demanding fluid flow at the first preselected pressure level, as pre ⁇ viously explained.
• the valve 14 upon shut-down of the engine automatically deactivates the clutch to unload the engine in preparation for later re-starting of the engine. This substantially eliminates problems associated with de-energizing the clutch in preparation for starting the engine and with starting the engine against the high loads placed thereon by an energized clutch.

Landscapes

• Engineering & Computer Science (AREA)
• General Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Fluid Mechanics (AREA)
• Mechanical Engineering (AREA)
• Hydraulic Clutches, Magnetic Clutches, Fluid Clutches, And Fluid Joints (AREA)
• Arrangement And Mounting Of Devices That Control Transmission Of Motive Force (AREA)
• Fluid-Pressure Circuits (AREA)
• Control Of Fluid Pressure (AREA)

Priority Applications (5)

Applications Claiming Priority (2)

Publications (1)

Family

ID=22154240

Family Applications (1)

Country Status (3)

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Citations (6)

Family Cites Families (2)

• 1980
  • 1980-03-12 WO PCT/US1980/000270 patent/WO1981002641A1/en unknown
  • 1980-03-12 JP JP55502383A patent/JPS57500309A/ja active Pending
• 1981
  • 1981-02-02 EP EP81100717A patent/EP0036070A3/en not_active Ceased

Patent Citations (6)

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