EP1413773A2 - Computerized electro-hydraulic proportional control device - Google Patents

Abstract

The control of the actuator (H) used with such as a crane is based around four electro hydraulic proportional control valves (13-16) connected in a daisy chain. The pressure of the output and return lines (7,8) are monitored (9,10) and signals fed to a control unit (CU). This provides control inputs to the proportional valves to regulate the speed.

Description

The invention relates to a computerized electrohydraulic proportional control device of the type specified in the preamble of claim 1.

In mobile hydraulics, computerized control devices with microprocessors are increasingly being used, the extreme performance of which for high-quality proportional control devices enables a large number of extraordinarily precise and individual control routines to be implemented, which are hardly possible with conventional control electronics.

The article "Elektronic-Hydraulic CAN-Bus Control Systems" by Ultronics Llmited, GL 526 RT, Englang, with the registration number UL / 1/1/500 / CP / 1/99, deals with hydraulic proportional control systems that are used communicate a CAN bus network with valve actuations. On the side titled "Power Stage", a proportional directional control valve arrangement is shown in cross section, which is integrated in a computerized electrohydraulic proportional control device for a hydraulic motor shown as a block diagram on the "System Schematic" side. In each case a 3/3 main directional control valve with pressure pilot control assigned to a working line is adjusted by an assigned proportional pilot directional control valve which is connected to the computer control. Pressure sensors are included in the working lines. Furthermore, adjustment path sensors connected to the computer control are assigned to the main directional control valves. As a special feature, mechanical decoupling of the inlet and outlet control edges is provided, so that the inlet and outlet could each be controlled extremely sensitively and individually. However, the two proportional pilot valves, each of which adjusts a main directional control valve, operate with the same pilot pressure, so that they influence one another and the mechanical decoupling of the control edges is at least partially nullified hydraulically.

The article "Classic versus new development?" of the magazine "fluid", January / February 2002, pp. 26 and 28, 29, discusses development trends in the control technology of mobile hydraulics, also with CAN bus concepts controlled by a computer for controlling pilot valves. For a valve assembly with two proportional pilot valves and two main directional control valves, the mechanical decoupling of the inlet and outlet control edges is discussed, which enables a very clean and individual inlet and outlet control if the pilot valves did not adjust the control edges in the same direction by the same control pressure. Although the control edges are mechanically decoupled, an over-regulating hydraulic coupling still acts in some cases, which prevents individual regulation of only the inflow or outflow.

In particular in the case of control devices for masts or mast slewing gear for cranes or concrete pumps, controlled braking of the discharge flow is necessary in particular if a pulling or pushing load acts on a mast section which cannot be controlled with sufficient certainty by a current regulator in the inlet, since the pulling one or pushing load temporarily reverses the kinematic relationships. Such a situation can e.g. occur if a mast section touches an obstacle when lowering or an extreme mast position causes a reversal of the direction of force.

In a control device known from US-B1-6 199 378, the proportional pressure control valves must each keep the working pressure or return pressure via slide pistons which are not leak-free in the shut-off positions. Therefore, the hydraulic consumer cannot be reliably blocked hydraulically. The proportional pressure control valves provided on the outlet side contain preloaded non-return valves that limit the maximum pressure and have priority over excessive pressure increases in the event of excessive pressure increases. This means that if the load in the hydraulic motor is reversed unintentionally, pressure medium can flow to the tank, although this is not controlled by the electronic control device. This leads to movements or changes in movement on the hydraulic motor, which cannot be controlled by the electronic control device. All proportional pressure regulating valves contain spools which are acted upon directly by the proportional solenoid without pressure pre-control. This requires large, expensive and strong proportional magnets, which makes it difficult to achieve sensitive control behavior.

In a control device known from US-A-5 875 701, the moving components of an earth-moving machine are actuated via hydraulic consumers, which are controlled in direction and speed by means of a joystick control with a microprocessor and unspecified valve devices. The microprocessor is fed with information on the relative angular positions of the components of the machine and the joysticks.

Further prior art is contained in EP-A-0 900 888 and US-B1-6 467 264.

The invention has for its object to provide a control device of the type mentioned, especially for a mast that is leak-tight in all shut-off positions, and in which to take into account difficult load conditions that may have a reversing effect on the hydraulic motor, the inlet and the outlet can be controlled independently of one another and individually, the performance of modern computer controls being used to adjust the control device to changing load cases.

The object is achieved with the features of claim 1.

In the two 2/2-way proportional control seat valves, each assigned to a working line, there is not only mechanical decoupling between each inlet and the outlet control edge, but there is no mutual influence of the two control seat valves on each other, since each seat valve only works in accordance with the Energizing its proportional magnet works independently of the other. The poppet valve design prevents any leakage in the shut-off position, so that the hydraulic motor cannot make any load-related wake or counter movements. Nevertheless, the two proportional control seat valves offer the possibility of a floating position by setting the two drain proportional control seat valves to a selective passage position via the computer control. The information from the actual pressure sensors in the working lines of the hydraulic motor is processed via the computer control so that the appropriate setting is made for each control seat valve. Thanks to the computer control, the control is able to adapt to changes in the load conditions (e.g. changes between pulling and pushing load) and to maintain the set speed of the hydraulic motor despite a simple construction of the valve assembly. In order to be able to make do with small, inexpensive and light proportional magnets with a large delivery volume and / or high working pressure, it is expedient to provide a pressure pilot control that can be activated against spring force via the proportional magnet in each control seat valve. In each proportional control valve, an individual pilot pressure of the pressure control can be set, which cannot be influenced by the pilot pressure in another proportional control valve. The pressure pilot control performs the actual control adjustment of the control seat valve depending on the energization of the proportional solenoid, which therefore requires less primary force. This has the advantage, for example, with the drain control poppet valves that when the load reverses (pulling load), the pilot pressure of the pressure pilot control increases and flanking the flow of the proportional solenoid, which can be adjusted at any time, to reduce the drain valve passage in order to maintain the set speed of the hydraulic motor ,

The two inlet-side control seat valves and the two outlet-side control seat valves are in each case structurally identical, preferably even identical. If necessary, even all four control seat valves are identical to one another, preferably even identical. Both options also reduce the control effort (e.g. as control signals transmitting messages) for the computer control.

Simple connection is possible if the computer control operates with a CAN node in a CAN bus system to which the four proportional magnets are connected in parallel via a data bus. The data bus preferably has a daisy chain configuration for the four proportional magnets, for which fewer or no high-quality processors are required.

In the case of a hydraulic motor, which is an articulated cylinder between two mast sections connected in a joint, a joint angle sensor, in particular for angle detection for a superordinate mast tip position, should also be expediently provided and connected to the computer control. The adjustment of the respective Proportional control poppet valves via the computer control can then take place additionally or dominantly with regard to the mast tip position or the angle between mast sections.

A pressure sensor for the inlet pressure to the inlet proportional control seat valves is also expediently connected to the computer control. The computer control then knows the pressure difference between the supply line and the working lines. With this information, the size of the valve passage (in the outlet and / or in the inlet) can be set even more precisely in order to achieve an ideal load-independent flow distribution (LUDV), i.e. a stepless and load-independent setting of the speed of the hydraulic motor, or just throttling precisely.

The variety of control routines of modern processors of a computer control can continue to be used profitably, even if an electric pump drive, and possibly a pressure sensor for the pump delivery pressure, are connected to a further CAN node of the bus system, so that the drive control or regulation of the pump via the Bus system is feasible.

In one embodiment, the pump can be a constant feed pump with an electrical bypass valve that is controlled from the bus system.

In another embodiment, the pump can be a pressure-constant control pump that can be switched electrically from the bus system to unpressurized.

In a further embodiment, the pump can be a control pump with an electrical flow rate and / or delivery pressure setting controlled from the bus system.

Fig. 1

ist ein Blockschaltbild einer computerisierten, elektrohydraulischen Proportional-Steuervorrichtung für einen Hydromotor, der beispielsweise ein Knickzylinder eines Masten eines Mobilkrans oder einer Betonpumpe ist.

An embodiment of the subject matter of the invention is explained with reference to the drawing.

Fig. 1

Fig. 3 is a block diagram of a computerized electrohydraulic proportional control device for a hydraulic motor which is, for example, an articulated cylinder of a mast of a mobile crane or a concrete pump.

In Fig. 1, a computerized, electro-hydraulic proportional control device S is used for speed and / or direction control of a hydraulic motor H, here an articulated cylinder of a mast M. The hydraulic motor H is arranged between two sections 1, 3 of the mast M. The two sections 1, 3 are at least pivotally connected to one another in a joint 2, so that an angle α between the sections 1, 3 can be adjusted by means of the hydraulic motor H.

The hydraulic motor H is fed from a pump 4, which is driven by an electric drive M, for example. A pressure line 5 leads from the pump 4 to two 2/2-way proportional control seat valves VZ1, VZ2. The pressure line 5 may continue to other consumers or control devices, not shown. A return line 6 leads to a tank T, which comes from two outflow-side 2/2-way proportional control seat valves VA1, VA2.

Two working lines 7, 8 each lead to the hydraulic motor H, each with a pressure sensor 9, 10 connected to a computer control CU (a converter which converts hydraulic pressure P into an electrical signal E). The pressure sensors 9, 10 are connected, for example, to a CAN node CK1 of a CAN bus system. If necessary, an angle sensor 11 is provided for the joint 2, which is also connected to the CAN node CK1 and serves to provide a higher mast tip position determined by angle detection.

Another pressure sensor 11 is connected to the pressure line 5 and is electrically connected to a further CAN node CK2 of the bus system, wherein the electric pump drive M can also be connected to the CAN node CK2.

The working line 7 branches off to the outlet-side proportional control valve VA1 and the inlet-side proportional control valve VZ1, with a branch in the branching branch to the inlet-side proportional control valve VZ1 in the direction of flow to the proportional control seat valve VZ1 non-leakage check valve 19 is arranged. Similarly, a check valve 19 'is also provided for the working line 8, which branches off to the proportional control seat valves VA2, VZ2.

Each proportional control valve VA1, VA2, VZ1, VZ2 has its own proportional magnet 13, 14, 15, 16. The proportional magnets 13 to 16 are connected in parallel to a data bus 20 to the CAN node CK1. If necessary, the data bus 20 is designed as a daisy chain. With each proportional magnet 13 to 16, a pressure pilot control 17 can be activated against the force of a valve spring 18, so that the proportional magnet adjusts the pilot pressure by adjusting the proportional control seat valve (servo effect).

Each proportional control valve VA1, VA2, VZ1, VZ2 defines its own valve passage (DA = drain passage in VA1, VA2; DZ = inlet passage in VZ1 and VZ2), the size of which can be varied by adjusting a control edge that is not highlighted in order to set the flow independently of the load, or if necessary to produce an adjustable throttle effect. In the shut-off position, the valve passage is leak-tight.

Since the proportional control seat valves are structurally separate from one another, the inlet and outlet control edges are also mechanically decoupled, and an individual pilot control pressure of the pressure pilot control 17 can also be set in each proportional control seat valve, which cannot be influenced by the pilot control pressure in another proportional control seat valve is.

In Fig. 1, no proportional magnet 13 to 16 is energized. All proportional control seat valves VZ1, VZ2, VA2 are held in their shut-off positions by the valve springs 18, in which they are leak-tight. The check valves 19, 19 'shut off without leakage. The hydraulic motor H is hydraulically blocked.

To increase the angle α, the proportional magnet 13 and the proportional magnet 16 are energized, possibly different from one another and as in the computer control Cu calculated or saved. If the angle α is to be reduced, the proportional magnet 14 and the proportional magnet 15 are energized. To brake an adjustment movement between the mast sections 1, 3, the current supply to the respective proportional magnet 15 or 16 is changed individually, for example in accordance with the information from the respective pressure sensor 9 or 10. If, for example, the angle α is reversed, a load direction change from a pressing to a pulling direction occurs Load on (determined via the pressure sensor 9 or via both pressure sensors 9, 10), then either the energization of the proportional magnet 15 and / or the energization of the proportional magnet 14 is reduced accordingly in order to maintain the set movement speed of the hydraulic motor H.

Claims (10)

Computerized electrohydraulic proportional control device for at least one hydraulic motor (H), in particular for a mast (M) of a crane or a concrete pump, with proportional control valves arranged between a pump (4) with tank (T) and the hydraulic motor (H) for adjustment the hydraulic motor movement speed and direction via variable valve passages (VA1, VA2, VZ1, VZ2) on the inlet and outlet sides, with the inlet and outlet control edges being mechanically decoupled, and with a computer control (CU ), to which at least pressure sensors (9, 10) in the two hydraulic motor working lines (7, 8) and the proportional magnets (13 to 16) of the proportional control valves are connected, characterized in that for each working line (7 or 8) A 2/2-way proportional control poppet valve (VA1, VA2, VZ1, VZ2) is provided on the inlet and outlet sides, which has a variable inlet for the working line (7 or 8). and has a variable drain passage (DA, DZ) that between the working line (7) or (8) and the inlet passage (DZ) a non-leakage check valve (19, 19 ') is arranged in the flow direction to the inlet passage, that when the valve is not energized Proportional magnets (13, 14, 15, 16) the inlet-side valve (VZ1, VZ2) is held in a leak-free inlet shut-off position and the outlet-side valve (VA1, VA2) in a leak-free outlet shut-off position, and that each valve (VA1, VA2 , VZ1, VZ2) has a pressure pilot control (17) which can be activated against the spring force (18) via the proportional magnet (13 to 16) and with which an individual pilot pressure which cannot be influenced by the pilot pressure in another valve can be set. Control device according to claim 1, characterized in that the two inlet-side valves (VZ1, VZ2) and the two outlet-side valves (VA1, VA2) are each constructed identically to one another, preferably identically. Control device according to claim 1, characterized in that all four valves (VA1, VA2, VZ1, VZ2) are constructed identically, preferably identically. Control device according to claim 1, characterized in that the computer control (CU) has a CAN node (CK1) in a CAN bus system (B), and that the four proportional magnets (13 to 16) are connected in parallel to a data bus (20) , preferably to a data bus designed in a daisy chain configuration. Control device according to at least one of Claims 1 to 4, characterized in that the hydraulic motor (H) is an articulated cylinder between two mast sections (1, 3) connected in a joint (2), and in that a joint angle sensor (11), preferably for Angle detection for a higher mast tip position, is provided and connected to the computer control (CU). Control device according to Claim 1, characterized in that a pressure sensor (11) which taps the inlet pressure to the inlet-side valves (VZ1, VZ2) is provided and is connected to the computer control (CU). Control device according to claim 4, characterized in that an electric pump drive (M) and the pressure sensor (11) tapping the pump delivery pressure are connected to a further CAN node (CK2) of the CAN bus system (B). Control device according to Claim 7, characterized in that the pump (4) is a constant feed pump with an electrical bypass valve which can be actuated from the bus system. Control device according to claim 7, characterized in that the pump (4) is a pressure-constant control pump and can be switched to pressureless, preferably electrically switchable to pressureless from the bus system. Control device according to claim 7, characterized in that the pump (4) is a control pump with electrical delivery flow and / or delivery pressure setting which can be actuated from the bus system.

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