Linde Aktiengesellschaft

Walter Kropp

Horst Deininger

Alfred Krusche

Wolfgang Grone

Rudolf Richter

The invention relates to a control valve for the control, independently of a load, of a hydraulic consumer with a distributing slide valve to control the direction of movement and the speed of movement of the consumer and a throttle valve associated with the distributing slide valve. The throttle valve, when there is a connection of a pump with the consumer, can be pressurized toward an open position by the pressure downstream of the throttle point of the distributing slide valve, and toward a closed position by the load pressure of the consumer and by a spring. The invention teaches that the object of providing a control valve that easily makes possible a restriction of the quantity of hydraulic fluid flowing out of the consumer to a reservoir and thus a control of the speed of movement of the consumer in the discharge direction independently of the load, can be accomplished if, when the consumer is connected with a reservoir, the quantity of hydraulic fluid flowing out of the consumer is restricted by the throttle valve. In one embodiment, when the consumer is connected with the reservoir, the throttle valve can be pressurized toward the closed position by the pressure upstream of the throttle point of the distributing slide valve, whereby the pressure acting in the direction of the closed position of the throttle valve can be set and varied by a valve device that generates a differential pressure.

Control valve

A hydrostatic drive system has a demand-responsive pump and at least one hydraulic circuit or consumer connected to it. Each consumer can be actuated by a directional control valve which acts as a throttle in intermediate positions. For the distribution of the delivery flow independently of the load, a pressure-maintaining valve is located upstream of the directional control valve. The pressure-maintaining valve can be controlled by a differential signal formed from a load pressure signal and a delivery pressure signal. The load pressure signal to the pressure-maintaining valve of the consumer can be changed by the output signal of a pressure reducing valve. One control surface of the pressure-maintaining valve can be pressurized with the output-side pressure of the pressure reducing valve which is located in a load pressure line. The output pressure of the pressure reducing valve can be adjusted by a spring and a variable control pressure.

Hydrostatic drive system

A hydrostatic drive system including a pump (1) and consumers (6, 8) which can each be actuated by a directional control valve (5,7) is disclosed. Each directional control valve (5, 7) is assigned a pressure compensator (9, 10) which can be controlled by a signal difference formed from a load pressure signal and a delivered pressure signal. The load pressure signal is derived from the highest of the load pressures occurring downstream of the directional control valves (5, 7), and the delivered pressure signal is derived from the pressure upstream of the directional control valves (5, 7). To limit the driving force and driving moment of at least one of the consumers, the signal difference across the pressure compensator (9) of at least one consumer (6) can be influenced by a controllable pressure output signal of an infinitely variable pressure control valve in such a way as to adjustably limit through-flow across the pressure compensator.

A hydrostatic drive system having consumers (6, 8) connected to a demand regulated pump (1) and actuated by a directional control valve (5, 7) is disclosed. The consumers can be connected downstream of the control valves via return valves to a load-sensing line (12). To provide for load-independent allocation of the delivered flow when the consumers are simultaneously actuated, each directional control valve (5, 7) is assigned a pressure balance (9, 10) which can be controlled directly or indirectly by a signal difference formed from a load pressure signal and a delivered pressure signal. To enable one or more of the consumers (6) to be supplied with pressure medium on a priority basis, so that no reduction in the speed of movement occurs, a priority valve (20) is connected into the LS-line (12) in such manner that in a first operating position of the priority valve (20) the line sections (12b) downstream of the non-return valve(s) of the non-priority consumer(s) (8) are connected to the LS-line (12), and in a second operating position they are connected to a line (4a) which conveys the delivered pressure of the pump (1).

A hydraulic system including a pump having a discharge line and a number of hydraulic energy consumers connected to the pump discharge line. A controller for the load-independent distribution of a pressure medium from the pump to the consumers includes a multiway valve located in the discharge line between the pump and each consumer to actuate the consumers. A pressure compensator for determining the flow of pressure medium to each multiway valve is located in the discharge line upstream of each multiway valve. Each pressure compensator is actuated as a function of a first pressure difference resulting from the pressure upstream of a multiway valve and the pressure downstream of the multiway valve and of a second pressure difference resulting from the discharge pressure from the pump and the highest load pressure of the consumers. At least one pressure difference of at least one pressure compensator is adjustable.

Control system for the load-independent distribution of a pressure medium

A control device for a drive unit, preferably the drive unit of a power vehicle, is provided having a hydrostatic transmission where the adjusting device of the latter and the adjusting device of the internal combustion engine are controlled by means of a servo piston loaded by control pressure, whereby the internal combustion engine is prevented during reversing from being adjusted to an increased power output through a circuit before the adjusting device of the hydrostatic transmission has passed through the zero-stroke position, and where the circuit has two shut off valves whose outlets are connected with a line, which are connected to the spring-side pressure chamber of the operating cylinder of the internal combustion engine through a multiway valve.

Reversible hydrostatic transmission pump with drive engine speed control

A hydrostatic drive with an adjustable pump and several consumers is provided in which one or several consumers simultaneously can be selectively connected with the pump, in which case the connection to a consumer can be effected by an arbitrarily actuable control valve having a throttling effect in the intermediate positions, where the loading of the adjusting element of the pump is controlled by a pump adjusting valve, which in turn is regulated by the pressure differential arising at the regulated control valve so that it is regulated to a constant pressure differential, where the highest prevailing pressure in a line between the regulated control valve and the regulated consumer is conveyed through a control pressure line to the control pressure chamber on the spring side of the pump adjusting valve and where a pressure limiting valve is connected to the pump delivery line and provided on the spring side with a control pressure chamber connected with the control pressure line (load-sensing signal line).

Hydrostatic drives

A multiway valve is provided having a load feedback wherein a pressure-reducing element that reduces the pressure conveyed to a connection through the valve with a control pressure signal line is controlled as a function of the displacement of a valve piston in the multiway valve.

Multiway valves with load feedback

A control for a power drive assembly having a primary energy source, a hydrostatic pump driven by the energy source and a consumer of energy has a multiway valve between the pump and consumer and a control pressure dependent valve receiving fluid from the pump controlling its position and connections between a source of pressure fluid and a spring biased operating cylinder connected to a control lever on the primary energy source controlling operation thereof.

Controls for power drive assemblies

A hydraulic or the like drive system which can include a variable-speed pump with at least one control element. The control element can be connected to a pump control piston arranged in a pump control cylinder, the position of which is determined by a control pressure. The drive system can further include a conveying conduit connected to the pump and a return conduit which leads to the respective reservoir, and can furthermore include control elements, with the conduit emanating from the pump are connected--by intervention of a respective branch line--several demand points which respectively can be connected to the conveying conduit by means of an in the respective branch line arranged, randomly movable valve. The valve has two auxiliary pistons arranged in the main piston of the valve and each auxiliary piston houses a reversing piston.

Slide valve for load sensing control in a hydraulic system

A hydraulic arrangement with a pressure medium source and at least two consumers connected to it is provided in which the sum of the streams consumed by the consumers can be greater than the maximum delivery stream of the pressure medium source, where one of the consumers is preferred and receives the full stream required by means of a special device and a second consumer is connected to a multiway valve that is controlled by control pressure, whereby, in order to arrive at a small cost-favorable multiway valve, the multiway valve in the device that causes the preference of the consumer is located between a low-pressure medium source and the control pressure chamber of an additional multiway valve that is hydraulically controlled against spring force and is installed in front of the second consumer, and that the spring-side control pressure chamber of this multiway valve is acted upon by the pressure in the control pressure line and the opposite control pressure chamber of this multiway valve is acted upon with the pressure of the stream flowing to the privileged consumer.

Dual consumer hydraulic mechanisms

A hydrostatic drive is provided having an adjustable pump connected with a pump servo positioned by a control pressure from a line connected between the consumer and an adjustable measuring restrictor which in turn is connected to a switching means which includes a plurality of hollow ended main spools in boreholes in a housing, and secondary spools in said hollow ends acting with radial passages in the main spool to form parallel connected restrictors.

Hydrostatic drive systems

A multiple consumer hydraulic device is provided having a pump and at least two consumers, where a multiway control valve throttling in the intermediate positions is located in front of each of these consumers and a hydraulically controlled additional valve is located in the line between the pump and this mulitway control valve and is acted upon in the closing direction by the pressure in front of this multiway control valve and is loaded in the opposite direction by the pressure of the assigned consumer in which case, in order to achieve a load-independent proportioning of the pump stream for both pumps with and pumps without load-sensing, the additional multiway valve is provided with two additional control pressure chambers, of which the one acting in the closing direction is acted upon by the pressure of the one of the consumers carrying the highest pressure, and the oppositely acting additional control pressure chamber is acted upon by the pressure in the delivery line of the pump.

Multiple consumer hydraulic mechanisms

A hydraulic spool valve is provided for controlling the flow of fluid between a pump, a consumer of hydraulic energy and a reservoir which spool has pressure controlled by-pass means by-passing fluid from the fluid inlet of the valve to tank while the valve is moving from a neutral to a work position and the reverse thereof at a pre-selected pressure level.

Hydraulic spool valves with controlled by-pass

A valve is provided, particularly as a part of a block control device, made up of an elongate housing having a longitudinal bore with spaced work chambers, inlet chambers and exhaust chambers intersecting the bore and an elongate cylindrical spool slidable in said bore, having a second bore in each end of said spool, a brake piston movable in each second bore, a pair of restrictor passage means one in said spool and one in said brake piston connecting the interior of said spool with both ends of each bore in the spool on opposite ends of the piston, a pair of spaced transverse passages at each end of the spool communicating with each bore in the spool and spaced to connect a work chamber and pressure fluid chamber at one end of the spool and a work chamber and exhaust chamber at the other end of the spool in a work position, an annular groove in the brake piston capable of connecting said spaced passages within the bore in the spool whereby in said work position pressure fluid flows from a pressure fluid chamber through said transverse passages to a work chamber at one end of the spool, and the pressure fluid from a pressure fluid chamber through said restricting passages to act on the brake piston to move it to position the groove between the passages at the other end of the spool to regulate flow of fluid between the work chamber and exhaust chamber in accordance with the relative pressure in the pressure fluid chamber.

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Sulzbach am Main, Germany

Walter Kropp