Abstract:
A hydraulic system (600) and method for reducing boom dynamics of a boom (30), while providing counter-balance valve protection, includes a hydraulic actuator (110), first and second counter-balance valves (300, 400), first and second control valves (700, 800), and first and second blocking valves (350, 450). A net load (90) is supported by a first chamber (116, 118) of the hydraulic actuator, and a second chamber (118, 116) of the hydraulic actuator may receive fluctuating hydraulic fluid flow from the second control valve to produce a vibratory response (950) that counters environmental vibrations (960) on the boom. The first blocking valve prevents the fluctuating hydraulic fluid flow from opening the first counter-balance valve. The first blocking valve may drain leakage from the first counter-balance valve.
Abstract:
A hydraulic system (600) and method for reducing boom dynamics of a boom (30), while providing counter-balance valve protection, includes a hydraulic cylinder (110), first and second counter-balance valves (300, 400), first and second control valves (700, 800), and a selection valve set (850). The selection valve set is adapted to self-configure to a first configuration and to a second configuration when a net load (90) is supported by a first chamber (116, 118) and a second chamber (118, 116) of the hydraulic cylinder, respectively. When the selection valve set is enabled in the first and second configurations, the second and first control valve may fluctuate hydraulic fluid flow to the second and first chamber, respectively, to produce a vibratory response (950) that counters environmental vibrations (960) of the boom. When the selection valve set is not enabled, the first and second counter-balance valves are adapted to provide the hydraulic cylinder with conventional counter-balance valve protection.
Abstract:
The invention relates to a hydrostatic drive system having a pump (1) and at least one consumer (6) that can be connected alternately to the pump (1) and a tank (3) by means of a directional control valve (4) that can be actuated by control signals (15, 16), in order to control the motion of a positive or a negative load (9) at the consumer (6). A counterbalance valve (5, 51, 60) is thereby disposed in the line (13) leading through the directional control valve (4) to the tank (3) of the negative connection of the consumer, wherein said counterbalance valve can be placed under a pressure that can be controlled by a programmable logic unit (31) when controlling a positive load.
Abstract:
Embodiments relate to braking high-speed rotational cutting equipment. In particular, some embodiments relate to forestry machinery having a cutting or mower apparatus, and further having a hydraulic brake. The brake includes a counterbalance valve which pressurizes fluid at the motor outlet to a predetermined level when flow of hydraulic fluid from a pump to a motor is discontinued. The hydraulic brake may include a restrictor orifice to reduce sudden pressure increases on the motor. The predetermined pressure level may be between about 2000 psi and about 4000 psi and the orifice may have a diameter of between about 0.025 and 0.040 inches. The counterbalance vent port can hydraulically connect to the motor case line. An anti-cavitation valve can be at the counterbalance valve port can supply fluid to the motor inlet after the flow from the pump discontinues. Additional embodiments include related hydraulic control systems and methods.
Abstract:
The present invention includes a control valve (10) for a pneumatic cylinder (12) having a piston (18), a first chamber (20) to be pressurised to effect a forward stroke of the piston and a second oppositely acting chamber (22) to be pressurised to effect a return stroke of the piston (18). The control valve (10) comprises a valve block (36) connectable to the second chamber (22), and has a valve spool (48) moveable axially therein. The control valve (10) also comprises a first conduit (38) through the block (36) and in fluid communication with the second chamber (22) of the cylinder (12) when attached thereto, where the first conduit (38) includes an axial passage through the spool (48) and is controlled by valve surfaces of the valve block (36) and spool (48). A pressure surface (56) of the spool (48) through which the axial passage passes is exposed to pressure fluid in the first conduit (38) such that pressure applied to the pressure surface (56) biasses the valve spool (48) in a first axial direction to maintain the first conduit (38) closed. The control valve (10) also comprises means for returning the spool in an opposite axial direction to open the first conduit (38), and a restricted bleed conduit (40) bypassing the first conduit (38). By providing the valve spool (48) with an axial passage it is possible easily to tune (adjust) the area of the pressure surface (56) of the spool (48) for a particular cylinder by suitably selecting the size of the axial passage: for a given valve spool, the larger the passage, the smaller the area of the pressure surface, and thereby the return pressure at which the valve opens can be selected.
Abstract:
A hydraulic circuit for construction machines which, in order to prevent a vacuum phenomenon which occurs in the hydraulic pressure chambers of hydraulic actuators, such as hydraulic cylinders and hydraulic motors, is provided with a back pressure regulating valve in an oil passage for returning oil to an oil tank from a direction switching valve, with a make-up means to feed the upstream working fluid to the hydraulic pressure chamber, wherein problems such as increased loss of hydraulic horse power and decreased output from the hydraulic actuator, caused by increase in the back pressure in the return oil passage, are eliminated. A make-up hydraulic source feeding compressed hydraulic fluid to the make-up hydraulic passage connected to the hydraulic chamber is provided in other than the return passage to the oil tank, and the back pressure regulating valve in the return oil passage is omitted.
Abstract:
A driving device for a hydraulic motor comprising a directional control valve (21) for supplying pressure oil discharged from a hydraulic pump (20) to a first port (25) or a second port (26) of a hydraulic motor (24) and returning oil returning from the second port or the first port to a tank (27) and a pilot pressure supplying valve (40) for controlling the directional control valve (21) wherein the directional control valve is of a pilot pressure selection type in which the valve is positioned, respectively, at a neutral position A by means of springs (32, 33), at a first position B by virtue of a pressure to a first pressure receiving portion (34), and at a second position C by virtue of a pressure to a second pressure receiving portion (35), wherein when the directional control valve is at the neutral position, the discharged pressure oil is supplied to the first and second ports via check valves (36, 37), when at the first position, the discharged pressure oil is supplied to the first port, while pressure oil at the second port is discharged therefrom into the tank, and when at the second position, the discharged pressure oil is supplied to the second port, while pressure oil at the second port is discharged therefrom into the tank, wherein the pilot pressure supplying valve is positioned at a neutral position F by means of springs (50, 51), and is switched to a first position G and a second position H by first and second drive means (52, 53), respectively, so as to supply pilot pressure to the first and second pressure receiving portions, and wherein when the pilot pressure supplying valve is positioned at the neutral position, the first and second pressure receiving portions communicate with the tank, when at the first position, the first port communicates with the first pressure receiving portion, while the second pressure receiving portion communicates with the tank and when at the second position, the second port communicates with the second pressure receiving portion, while the first pressure receiving portion communicates with the tank.
Abstract:
A brake device for an inertia body driving hydraulic circuit characterized in that first and second oil ports (11, 12) are formed in parallel to each other in a housing (10) so as to connect said first and second oil ports to an inertia body driving actuator (18), that said first and second oil ports are caused to communicate with each other via a communicating oil port (13), which is then caused to communicate with a tank port (14), that first and second mounting holes (15, 16) are formed in said housing in such a manner that they open to said first and second oil port and are concentric with said communicating oil port, and that first and second suction safety valves (17, 17) having suction and relief functions are provided in said first and second mounting holes, respectively. With this brake device, since the first and second oil ports are formed in parallel to each other in the housing, the first and second oil ports are made to communicate with each other via the communicating oil port, and the suction safety valves are respectively provided in the first and second mounting holes which are concentric with the communicating port, the shape of the oil ports are simple for case of working. Moreover, pressure oil in the tank port is sucked into the first and second oil ports in a linear fashion via the communicating oil port to reduce the pressure loss, thereby making it possible to positively prevent cavitation.