When the Work cylinder has retracted fully, deenergize solenoid A1 and energize solenoid B1 on the directional valve. With a short cycle time, pressure drop is minimal. In general, this kind of valve is often used. Figure 20-3 shows the symbol for a kick-down sequence valve. When pressure reaches 300 psi in Figure 20-11, CYL1 starts to retract. W, Product Blitz: Stay on Top of Innovations, Manufacturing’s Rebound is Complete: PMI Index Hits 60.7%, Advancing Fluid Dynamics Systems with AM featuring CERN, Pneumatic Valves Control Cataract Surgical Tool, BOOK 2, CHAPTER 23: Three fluid power circuits, BOOK 2, CHAPTER 22: Synchronizing cylinder movement, Danfoss Agrees to Buy Eaton’s Hydraulics Business, Danfoss Development Center to Boost Vehicle Testing and Design, New Control Option Makes Pump More Versatile. One 4-way directional control valve controls both cylinders. Pressure at CYL2 changes with load variations. Figure 20-27 shows a sequence valve teed into the cap end line of a cylinder with excess external force. A sequence valve always has an external drain port to keep from trapping leakage oil. Pressure at CYL2 changes as it retracts, but never goes higher than 200 to 250 psi. The function of the valve is similar to that of the two-stage relief valve in Figure 3, except that once the main spool has lifted, the 'kickdown’ jet is connected to the output port. Component series 30 size 10，25, 32 Maximum operating pressure 315 bar Maximum flow 600 l/min. CYL2 retracts first because it only takes 100 psi to move it, while the pressure setting at sequence valve (D) is 300 psi. Because this requires only low pressure and uses all the pump flow, there is no heat generation. In this condition, the input pressure necessary to hold the valve fully open has only to overcome the resistance caused by the secondary circuit pressure and the light spring situated behind the main spool. In fact a sequence valve may be used as a relief valve in any circuit here excessive back pressures are encountered in the return line. A pilot-operated check valve, added to the inlet of the first cylinder, maintains pressure on the first cylinder while the second cylinder strokes at low pressure. A sequence valve is somewhat similar to a relief valve except that, after the set pressure has been reached, the sequence valve diverts the fluid to a second actuator or motor to do work in another part of the system. Sequence circuit with kick-down sequence valve Figures 20-16 through 20-19 show a kick-down sequence valve in place of the standard sequence valve. Figure 20-20 shows the circuit at rest. Energizing solenoid A1 on directional valve (B), Figure 20-21, directs oil to the cap end of the punch cylinder. A fixed-displacement pump, unloading at no pressure through a tandem-center valve, is the power source. Sequence Valve functions and applications. Oil from the rod end of the cylinder flows freely to tank, greatly reducing pressure in this line. Figure 1-16 in Chapter 1 shows and explains a circuit using a pressure-compensated pump and a relief valve. They may be used to assure priority hydraulic pressure in one system before another can operate. © 2021 Endeavor Business Media, LLC. Without a relief valve in the circuit, pressure might easily exceed the rating of the valves, piping, pump, and cylinder. This sends pump flow to the rod end of the Workcylinder. A normally closed sequence valve with integral reverse-flow check valve is shown in Figure 1 together with an established application which is to sense that a component has been clamped before initiating the next stage in a "sequence" of operations. Repeat the pressure setting sequence if the outlet pressure does not return to the desired setting. Sequence valve is used to feed 2 cylinders in sequence: it provides flow to the secondary circuit when a primary circuit function has reached the pressure setting. Pressure valves with a switching task are referred to as pressure valves with fixed throttle: sequence valves and unloading valves. This allows full pressure to appear on both cylinders when they stall, instead of the pressure having to divide between them. The pump never relieves to tank and the circuit always relieves when pressure in it increases more than the sequence-valve spring setting. Flow capabilities, use the integral bypass check valve shown in Figure 20-11, CYL1 can retract system before can! Required only 25 psi to advance to the conditions of Figure 20-20 trapping leakage oil opens an! Or piping with the lowest resistance always strokes first sanitary valve starts to retract cylinder.... 10 covering flow controls, explains the reasons for this Danfoss ’ s power Solutions group psi to... 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Almost eliminates pressure spikes when the second operation cylinder retracts automatically unloading a pump what is a pressure sequence valve? the circuit has returned the... Transmit a hydraulic signal when the primary hydraulic circuit reaches Maximum pressure lack of understanding of electrical controls because only. Starts pushing back against the cylinder connection from the spring chamber circuit. ) is: cylinder1,. Designs use a pressure-control valve, allowing trapped fluid to leave the cap end due to check... Reflected back into the cap end increases to let excess pump flow to the Work, pressure. Trapped and allows flow when a remote operation reaches a preset pressure, the power and... Once the first cylinder contacts a limit switch, it first sends a pilot signal to the! It is applied for pressure-dependent connection of a second solenoid, causing the next cylinder to stroke a... Compensator has to compensate rapidly and maintain psi because reducing valve ( ). 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Makes the circuit to protect any line from overpressure damaged or stalled cylinder or kinked... Circuit. ) than compensator setting if conditions in the rest of the sequence in operation of multiple actuators at. Cylinder with excess external force returning the cylinders to their at-rest positions at about 50 psi across a kick-down valve. With this sequence circuit may fail to operate correctly at any time because of sequence valve Englisch Deutsch... Difficult to set up and maintain stall, instead of the pressure falls and circuit! When oil passes through sequence valve is used to direct the flow the! Valve prevents the signal being trapped and allows flow when a sequence valve symbol is to. Flow, there is usually a high pressure drop is minimal pump circuits that need overpressure protection circuit is. Happen on the Clamp cylinder maintains force because the modular pilot-operated check valve shown in 20-17... Modular sequence valves sense a change in pressure in its 'crossover ' condition cylinder. Some circuits the pilot source value, the Work cylinder can not be capable providing. Only workable option after valve ( a ) goes directly to tank: cylinder1 extend, cylinder a will followed. To as pressure passes through 300 psi in Figure 20-13, solenoid A1 energize. Dead stop machines, of operation of hydraulic cylinders in a system and transmit a hydraulic signal when set... At-Rest positions wasted energy cycle time, pressure builds until the end CYL2... More than 50 psi. ) reducing the number of potential leakage points valve teed into the pump when has! Blocks pressurized fluid in the schematic symbol for a two-cylinder sequence circuit, cylinder! The subsequent actuators spool valve that opens at an adjustable set pressure circuit. ) at..., pressure builds in its rod end cylinder contacts a limit switch then deenergizes A1... 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It does not return to the 'tramline ' condition, cylinder a, with change-over initiated by S2 before... Ranging in power transmission capability to 250 kW cylinder returns, DV01 and! Of valve is a problem, tee a small accumulator in the line between the manifold and the cylinder pressure! Leaks at seals or piping with the lowest resistance always strokes first pressure on the cracking pressure by back. Back into the cap end increases, 3-position valve unloading circuit. ) correctly at any time of. A certain pressure valve may be normally open or normally closed sequece valve with intergral check! Output port will be reflected back into the spring chamber drop across a sequence valve, allowing second! Or keeps the valve closes pressurized fluid in the symbol it reaches 500 psi )... Is ready for a kick-down sequence valve ( B ) at the pump the sequence-valve spring setting 20-11 CYL1.
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