Abstract:
An apparatus for controlling an electrohydraulic system of a work machine having an engine that drives a variable displacement pump is disclosed. A pump displacement setting device produces a pump command signal indicative of a desired displacement of the variable displacement pump. An engine speed setting device produces an engine command signal indicative of a desired rotational speed of the engine. A power manager receives the pump and engine command signals, determines an efficient engine speed and pump displacement, and produces an engine control signal that decreases the engine speed to the efficient engine speed and a pump control signal that increases the pump displacement to an efficient pump displacement, while maintaining a substantially constant pump flow rate.
Abstract:
A control device for variable hydraulic machines, and specifically for variable axial piston machines equipped with a servo system that is connected to a swash plate so that the discharge/displacement volume is infinitely variable. The hydraulic machine is equipped with a sensor that detects the piston displacement and is connected with an electronical control unit that controls the swash angle position of the swash plate and is pressure controlling the servo system by an electrohydraulic converter. A method for the infinite controlling of the volume flow of hydraulic machines, by which the servo system is connected to the swash plate of the hydraulic machine, and by which a conduction of a signal from a sensor to the control unit, a pressure controlling of the servo system by an electrohydraulic converter as well as the controlling of the swash angle position of the swash plate by the electronical control unit is realized.
Abstract:
A capacity control apparatus for a variable capacity hydraulic pump including: a capacity control cylinder having a capacity control piston for driving a capacity control member of the hydraulic pump, with a large diameter chamber and a small diameter chamber disposed at both sides of the capacity control piston, and driving the capacity control piston with a pressure fluid that is supplied into the larger diameter chamber, in a direction in which the capacity of the hydraulic pump may be reduced and for driving the capacity control piston with a pressure fluid that is supplied into the small diameter chamber, in a direction in which the capacity may be increased; a passage for the small diameter chamber to communicate with a pump discharge path; at least one control valve for controlling the capacity of the hydraulic pump by selectively communicating the large diameter chamber with either a pump pressure discharge path and a reservoir; and a variable throttle valve in a passage with the at least one control valve, in which the variable throttle valve is switched into a first state in which a throttled area of aperture in inverse proportion to a self discharge pressure of the pump discharge path is established and into a second state in which a predetermined throttled area of aperture that is independent of the self discharge pressure is established in response to an external signal.
Abstract:
A hydraulic system for driving an axial piston type hydraulic motor wherein a swash plate can tilt at a right angle relative to a shaft. The hydraulic system comprises a swash plate cylinder; a double-acting swash plate piston disposed in the swash plate cylinder; one rod end of which is connected to the swash plate; a pair of springs disposed in the swash plate cylinder for biasing the swash plate piston; a swash plate piston control valve for selectively connecting one of the swash plate piston chambers to a hydraulic pump or, alternatively, for interconnecting the chambers of the swash plate piston; an inlet passage installed between an inlet port of the hydraulic motor and a hydraulic pump; an outlet passage installed between an outlet port of the hydraulic motor and a tank; a main control valve installed in the inlet passage for opening or closing the inlet passage in response to a predetermined signal; a passage switching valve installed in the outlet passage for opening or closing the outlet passage in response to a predetermined signal; a bypass passage installed in the outlet passage wherein each end of the bypass passage is connected to a predetermined position before and after the passage switching valve; and a relief valve installed in the bypass passage.
Abstract:
The invention relates to a hydraulic control valve block in standard configuration having a first control valve (2) and a second control valve (3), functionally cooperating with the first control valve and connected therewith via pressure medium channels (28-31, 33), having a valve piston (5) which is controlled on the one hand by a hydraulic control pressure in a pressure chamber (25) and on the other hand is acted upon by a spring pressure part (7). In order to reduce the construction and installation costs of the control valve block, whilst employing a remotely controllable seat valve, and maintaining its functions, it is provided in accordance with the invention that a supplementary pressure medium channel (36) is formed in the control valve block and that the spring pressure part (7) of the second control valve (3) is replaced by an electrically controllable seat valve (60.1; 60.2) having an electromechanical control part (66.1; 66.2) and at least two hydraulic connections (63.1; 64.1) as valve inlet (63) and valve outlet (64.1; 64.2), and in that the valve piston (5) of the second control valve (3) is deactivated and therewith, at the same time, one (64.1; 64.2) of the two hydraulic connections (63, 64.1; 64.2) of the seat valve (60.1; 60.2) is connected to a hydraulic connection (T) already present and the other hydraulic connection (63) is connected to the supplementary pressure medium channel (36).
Abstract:
A system for the transport of high solids sludge includes a positive displacement pump for pumping sludge through a pipeline. The volume of sludge transported is accurately measured by determining the fill percentage by using a material flow signal, measured time intervals, hydraulic fluid pressure, or hydraulic fluid flow rate during each pumping cycle.
Abstract:
A system and method for controlling operation of a sludge material handling system is disclosed. The sludge material handling system includes a positive displacement piston/cylinder pump, a sludge material feed system which delivers sludge material to the pump, and a sludge material disposal system which receives and disposes of sludge material from the pump. A first parameter is sensed, the first parameter bearing a known relationship to an actual volume of sludge material delivered during a pumping cycle. An output value is determined from the first parameter. A control signal is provided as a function of the output value.
Abstract:
A system for the transport of high solids sludge includes a positive displacement pump for pumping sludge through a pipeline. The volume of sludge transported is accurately measured by determining the fill percentage during pumping cycle.
Abstract:
An electro-hydraulic control for a hydrostatic transmission including a variable displacement hydraulic pump and fluid operable servos to vary the displacement of the pump. The electro-hydraulic control is in series between the charge pump and the standard manual controller and determines the maximum pressure of the charge fluid ported to the standard controller. The electro-hydraulic control includes a spool biased toward a first position to port fluid from the charge pump to the standard controller, and biased toward a second position to relieve to tank the pressure of fluid ported to the manual controller. The biasing toward the second direction is accomplished, in part, by pressure in a fluid chamber exerting a biasing force on the spool, the fluid chamber being in communication with drain through a variable orifice which is variable in response to a pressure command signal. This signal is generated by control logic including a torque command signal generator which is variable to correspond to a maximum desired input torque setting and circuitry providing a torque approximation signal representing the product of pump displacement and the instantaneous pressure command signal. The circuitry compares the torque command and torque approximation signals and generates a new pressure command signal tending to minimize the difference between the torque command and approximation signals. As a result, the commanded maximum system pressure varies such that the product of maximum system pressure and pump displacement (equal to input torque) is constant, for a given input torque setting.
Abstract:
A variable displacement compressor includes a plate having a variable inclination angle, and a piston engaging the plate. The piston reciprocates within a bore of the compressor in accordance with a rotation of the plate, and the piston has a stroke length which is determined by the inclination angle of the plate. The compressor also includes a sensor positioned adjacent to the piston. The sensor generates an output signal when a predetermined portion of the piston is aligned with the sensor. The compressor also includes a processing unit operationally coupled to the sensor. The processing unit estimates the inclination angle of the plate based on the output signal from the sensor.