DE102008019501B4 - Electrohydraulic control arrangement - Google Patents

Abstract

Electrohydraulic control arrangement for controlling a hydraulic consumer (3), comprising a fluid pump (12) adjustable in its displacement volume, a variable-speed electric drive (10) coupled to it for driving the fluid pump (12), a p / Q controller (20) is arranged to provide, based on a desired pressure value and / or a volumetric flow setpoint, a drive control value for the displacement volume of the fluid pump (12), a speed command element (22) providing a speed command value, and a drive control device (14) which commands an electric drive motor of the speed reference, characterized in that at least the p / Q controller (20) and the speed selector member (22) are structurally combined in a common housing.

Description

The invention relates to an electro-hydraulic control arrangement for controlling a hydraulic consumer according to the preamble of patent claim 1.

Electro-hydraulic drives come e.g. For applications in which high actuating forces with small dimensions of the actuators and precise control of the hydraulically adjusted machine part is required.

A concept for the control of the hydraulic consumers of an injection molding machine is in the EP 0 403 041 A2 represented by the applicant. A constant displacement pump is directly connected to a hydraulic load in the manner of a hydraulic power / travel ratio. The fixed displacement pump is actuated by means of a variable speed, electric servo drive. The speed control loop of the servo drive is subordinate to a position control or a pressure control of the consumer.

Especially when holding a closing pressure, a high torque is required at very low speeds to keep high pressure by means of the constant pump. A disadvantage of this drive concept is therefore that a powerful, large-sized and therefore expensive servo motor is required, which can muster sufficient torque even at low speeds:

Another electrohydraulic drive for an injection molding machine is in the EP 0 464 286 B2 described. Various consumers, such as piston-cylinder units for closing the mold and for the material feed in the injection device and for driving a screw are controlled by means of a variable displacement pump and a valve unit. The variable displacement pump is operated in the known manner as part of a flow control or pressure control. Variable displacement pumps with an associated control unit are offered by Bosch Rexroth AG under the name SYDFEE - see data sheet RE 30630 / 06.06. The drive described in the aforementioned patent also has a variable speed electric motor for driving the variable displacement pump. The need for pressure medium, ie the required flow rate of the variable is calculated in advance for each phase of the injection molding process. The flow rate values are converted into speed values for the electric motor and stored in a flow control unit. The sequence control device controls the electric motor by means of the predetermined speed values.

The EP 1 236 558 B1 discloses an electro-hydraulic drive for a cyclically operated machine in which a variable displacement pump and a variable speed electric motor for driving the pump are combined. The speed of the electric motor is determined in a learning phase from the pressure setpoint specifications and from the flow rate setpoint specifications during a machine cycle. In the learning phase, the electric motor runs at the highest rated speed and p / Q control is only performed by the pump controller. After the learning phase, the speed of the engine is varied within the engine cycle, with the proviso to be able to meet the respective pressure setpoint specifications and flow setpoint specifications with reduced engine speed.

It is the object of the present invention to provide a simply controllable electro-hydraulic control arrangement.

This object is achieved by an electro-hydraulic control arrangement with the features of claim 1.

According to the invention, in an electrohydraulic control arrangement with an adjustable fluid pump and a coupled variable-speed electrical drive, with a p / Q controller which is set up to provide a drive control value for the displacement volume of the fluid pump on the basis of a pressure setpoint and / or a volumetric flow setpoint a Drehzahlvorgabeglied, which - eg due to a p / Q request cycle - provides a speed setpoint, and with a drive controller that drives a motor of the electric drive based on the speed setpoint, at least the p / Q controller and speed selector member are structurally combined in a common housing.

As a result, a compact structural unit is made available, which can control both the actuator of the variable displacement pump - usually a pilot valve - as well as the drive control unit of the electric drive. The wiring effort is significantly lower compared to a separate arrangement of p / Q controller and speed selector member. It can be exchanged and taken into account with little effort, all signals that are required for optimal combined control of the variable displacement pump and the electric drive. Such signals include, for example, pressure values (p), delivery flow values (Q) or a swivel angle signal (a) of the variable displacement pump or a pilot control value for the pilot valve, a rotational speed (n) or a torque required on the variable displacement pump. Setpoints and actual values can be taken into account. Compared to a higher machine control, a single interface can be provided, which also the interface of conventional p / Q controller - see data sheet RE 30630 / 06.06 - as far as possible.

Further advantageous embodiments are specified in the subclaims.

According to an advantageous development of the present invention, at least the p / Q controller and the speed selection element are combined in a common electronic unit, in particular a single electronic circuit. In particular, when using digital electronic units, the p / Q controller and the speed selection element are preferably realized in a single microcontroller. This allows particularly easy access of both components to the commonly used control and regulation parameters.

According to a particularly preferred embodiment of the present invention, the p / Q controller, the speed selection element and a valve amplifier, which controls a pilot valve of the variable displacement pump, are combined in one common housing. A particularly advantageous variant is the integration of said components into an electronic unit arranged on the pilot valve - a so-called on-board electronic unit (OBE). As a result, the number of separately available electronic units is kept as low as possible.

Similar advantages are obtained when the p / Q controller and the speed selection element are integrated in the drive controller of the electric drive.

Preferably, the p / Q controller and speed selector member share a common interface with a higher level machine controller, e.g. a PLC or a PLC. The interface preferably corresponds largely to the interface of a conventional p / Q controller, i. Pressure setpoints and / or flow rate setpoints are transmitted. The interface may be analog or digital, e.g. be executed as a fieldbus. This facilitates each of the control of the control arrangement according to the invention by the higher-level machine control.

Preferably, a speed setpoint value is determined in the speed selection element on the basis of a pressure setpoint and / or delivery setpoint value transmitted via the interface. From the point of view of the superordinate machine control, the control arrangement according to the invention therefore behaves on the one hand like a conventional pressure / delivery-controlled variable displacement pump, on the other hand a reduced noise level and energy savings with unchanged machine control are possible.

An optionally required synchronization signal, which indicates, for example, a start of the machine cycle, can be made available by the higher-level machine control system with little effort. Such a synchronization signal is eg when using a learning cycle, like him EP 1 236 558 B1 describes helpful. However, the synchronization signal can also be used, for example, in such a way that the p / Q controller informs the machine control when a certain control state has been reached.

The invention will be explained in more detail below with its further details with reference to the embodiments illustrated in the figures.

• 1 ein vereinfachtes Schaltbild einer hydraulischen Steuerung für einen hydraulischen Verbraucher mit einer Verstellpumpe, mit einem drehzahlvariablen elektrischen Antrieb und mit einer Ansteuerschaltung für das Antriebssteuergerät des elektrischen Antriebs, welche in einer Ventilelektronik des Pilotventils integriert ist,
• 2 eine Variante der hydraulischen Steuerung nach 1, bei der ein Regler für die Verstellpumpe im Antriebssteuergerät integriert ist, und
• 3 eine Abwandlung der in 1 und 2 dargestellten hydraulischen Steuerungen, bei der eine baulich eigenständige Regelelektronik vorgesehen ist, welche sowohl das Pilotventil als auch das Antriebssteuergerät ansteuern kann.

Show it:

• 1 a simplified circuit diagram of a hydraulic control for a hydraulic consumer with a variable displacement pump, with a variable speed electric drive and with a drive circuit for the drive control unit of the electric drive, which is integrated in a valve electronics of the pilot valve,
• 2 a variant of the hydraulic control after 1 , in which a controller for the variable displacement pump is integrated in the drive control unit, and
• 3 a modification of the in 1 and 2 shown hydraulic controls in which a structurally independent control electronics is provided which can control both the pilot valve and the drive control unit.

In the 1 is a hydraulic axis 1 a stationary manufacturing machine shown. This will be one or more hydraulic consumers 3 from a hydraulic control 5 supplied with pressure medium. The hydraulic control 5 in turn is from a higher level machine control 7 , eg a programmable logic controller (PLC) or a logic controller (PLC), by means of set value commands 8th in terms of the consumer 3 to be dispensed flow Q_soll or the pressure to be provided p_soll.

The hydraulic control 5 includes an electric motor 10 , which is the variable displacement pump 12 drives. The electric motor 10 - For example, an asynchronous motor - is by a drive control unit 14 , whose main component is an inverter FU, driven. The input value of the drive control unit 14 is a target speed of the electric motor 10 , The drive control unit 14 outputs a three-phase current corresponding frequency f_soll.

On the housing of the variable displacement pump 12 is a pilot valve 16 attached, which the Adjustment mechanism of the variable displacement pump 12 hydraulically operated. The pilot valve 16 is usually an electromagnetically actuated 3/2-way proportional valve. At the pilot valve 16 , possibly on the solenoid of the pilot valve 16 is a valve electronics 18 , a so-called Ob board electronics OBE attached. In the valve electronics 18 - so in a compact, the valve 16 attached housing - are a p / Q regulator 20 , a speed defaulting member 22 and a valve amplifier 24 integrated. The only interface 26 between the illustrated hydraulic control 5 and the machine control 7 is also located on the valve electronics 18 ,

The p / Q controller 20 generates among other things by means of the setpoints Q_soll and p_soll a control signal valve_soll for the pilot valve 16 which is the valve amplifier 24 for actuating the pilot valve 16 is supplied. The speed selection element 22 generates among other things by means of the setpoints Q_soll and p_soll a speed setpoint speed_soll, which the drive control unit 14 is supplied. Other parameters that can be used as a basis for determining the actuating signals are, for example, a pressure actual value, a delivery actual value or a swivel angle signal (a) of the variable displacement pump or a control control value for the pilot valve, a rotational speed (n) or a torque required on the variable displacement pump. These parameters are not shown in the figures for the sake of clarity. Such parameters - including all about sensors of the valve electronic 18 typically supplied actual values - can within the valve electronics 18 be made available with little effort and stand the components p / Q controller 20 and speed selector 22 for optimal control behavior. Examples, such as the control signal Valve_soll for the pilot valve 16 and how the speed setpoint speed_soll can be determined are in the EP 1 236 558 B1 explained.

In this embodiment, the valve electronics 18 a digital control circuit which has a microcontroller. The p / Q controller 20 and the speed defaulting member 22 are implemented as application programs on the microcontroller. This makes it possible for the control and regulating behavior of the valve electronics 18 to implement a variety of variants and the system of hydraulic control 5 optimally adapted to the machine characteristics. In addition, the acquired control parameters are readily available to all application programs.

A data exchange between p / Q controller 20 and speed selector 22 is very easy - without cabling.

Alternatively, it is also conceivable to use the p / Q controller 20 as an analog controller and the speed selection element 22 with a very simple microcontroller or programmable logic (eg FPGA) to implement. Preferably then the p / Q controller 20 and the speed defaulting member 22 on a circuit board or on eg connected by means of plug contacts boards, in the housing of the valve electronics 18 , housed.

Based on 2 a second embodiment will be described. This differs above all with respect to the arrangement of individual components of the first embodiment described above. The basic structure, the functionality and the described modifications can be transferred.

The valve electronics is constructed in a simpler manner according to the second embodiment and essentially comprises the valve amplifier 24 , This can be done on the pilot valve 16 be attached or be provided separately as a control cabinet module. The drive control unit 34 owns compared to the drive control unit 14 extended functionality. It not only serves the electronic control of the inverter FU but also contains the p / Q controller 20 as well as the speed selection element 22 , The only interface 26 the illustrated hydraulic control 5 to the higher-level machine control 7 is on the drive control unit 34 ,

The p / Q controller 20 forms the control valve_soll for the pilot valve 16 , This value is the valve amplifier 24 fed. The speed selection element 22 forms the speed setpoint speed_soll, which is within the drive control unit 34 is used to control the inverter FU.

On in the drive control unit 34 Usually existing microcontroller is designed so that it not only the control of the inverter FU but also the p / Q controller 20 and the speed defaulting member 22 as applications can perform. Used in the drive control unit 34 a very simple microcontroller, could be the p / Q controller 20 as analog controller in the drive control unit 34 , ie be integrated in the electronic circuit or in the housing.

A third embodiment shows the 3 , This in turn differs above all with respect to the arrangement of individual components of the embodiments described above. The basic structure, the functionality and the described modifications can be transferred.

The valve electronics are simple according to the third embodiment and essentially comprises the valve amplifier 24 , This can be done on the pilot valve 16 be attached or be provided separately as a control cabinet module. Also the valve control unit 14 has a simple structure and includes, as described in the first embodiment, predominantly the inverter FU and its control electronics.

The p / Q controller 20 and speed selector 22 are in contrast in their own separate control electronics 40 available. The control electronics 40 owns the only interface 26 the illustrated hydraulic control 5 to the higher-level machine control 7 , The p / Q controller 20 forms the control valve_soll for the pilot valve 16 , This value is the valve amplifier 24 fed. The speed selection element 22 forms the speed setpoint speed_soll, which is the drive control unit 14 is supplied.

The control electronics 40 is an electronics module, eg for the control cabinet installation. It contains a microcontroller which controls the p / Q controller 20 and the speed defaulting member 22 as applications can perform. Alternatively, it is also conceivable to use the p / Q controller 20 as an analog controller and the speed selection element 22 with a very simple microcontroller or programmable logic (eg FPGA) to implement. Preferably then the p / Q controller 20 and the speed defaulting member 22 on a board or on eg connected by means of plug contacts boards in the housing of the control electronics 40 , housed.

According to the invention, in an electrohydraulic control arrangement with an adjustable fluid pump and a coupled variable-speed electrical drive, with a p / Q controller which is set up to provide a drive control value for the displacement volume of the fluid pump on the basis of a pressure setpoint and / or a volumetric flow setpoint a Drehzahlvorgabeglied, which - eg based on a P / Q request cycle - provides a speed setpoint, and with a drive controller that drives a motor of the electric drive based on the speed setpoint, at least the p / Q controller and speed selector member are structurally combined in a common housing.

As a result, a compact structural unit is made available, which can control both the actuator of the variable displacement pump - usually a pilot valve - as well as the drive control unit of the electric drive.

LIST OF REFERENCE NUMBERS

1

hydraulic axis

3

hydraulic consumer

5

hydraulic control

7

machine control

8th

Setpoint

10

electric motor

12

variable

14

Drive controller

16

pilot valve

18

Valve electronics OBE

20

p / Q controller

22

Speed control element

24

valve amplifier

26

interface

34

Drive controller

40

control electronics

Claims (11)

Electrohydraulic control arrangement for controlling a hydraulic consumer (3), comprising a fluid pump (12) which can be adjusted with respect to its displacement volume, a variable-speed electric drive (10) coupled thereto for driving the fluid pump (12), a p / Q controller (20), which is arranged to provide a drive control value for the displacement volume of the fluid pump (12) on the basis of a desired pressure value and / or a volume flow setpoint, a speed selection element (22) which provides a speed setpoint, and a drive control device (14) which controls an electric motor Drive on the basis of the speed setpoint, characterized in that at least the p / Q controller (20) and the Drehzahlvorgabeglied (22) are structurally combined in a common housing. Electrohydraulic control arrangement according to Claim 1 , characterized in that at least the p / Q controller (20) and the speed selection member (22) in a common electronic unit (18; 34; 40 are summarized. Electrohydraulic control arrangement according to Claim 2 , characterized in that at least the p / Q controller (20) and the speed setting member (22) are combined into a single electronic circuit. Electrohydraulic control arrangement according to one of Claims 1 to 3 , characterized in that at least the p / Q controller (20) and the Speed input member (22) are realized in a single microcontroller. Electrohydraulic control arrangement according to one of Claims 1 to 4 , characterized in that the p / Q controller (20), the Drehzahlvorgabeglied (22) and a valve amplifier (24), which controls a pilot valve (16) of the variable displacement pump (12), are combined into a common housing. Electrohydraulic control arrangement according to Claim 5 , characterized in that the p / Q controller (20), the Drehzahlvorgabeglied (22) and the valve amplifier (24) in an on the pilot valve (16) arranged electronic unit (18) are summarized. Electrohydraulic control arrangement according to one of Claims 1 to 4 , characterized in that the p / Q controller (20) and the Drehzahlvorgabeglied (22) in the drive control unit (34) of the electric drive (10) are integrated. Electrohydraulic control arrangement according to one of Claims 1 to 4 , characterized in that the p / Q controller (20) and the Drehzahlvorgabeglied (22) together own a housing (40), and that the drive control unit (14) and a valve amplifier (24) of a pilot valve (16) of the variable displacement ( 12) are each separate therefrom. Electrohydraulic control arrangement according to one of Claims 1 to 8th , characterized in that an interface (26) is provided to a higher-level machine control (7) in the common housing. Electrohydraulic control arrangement according to Claim 9 , characterized in that in the speed command element (22) due to a via the interface (26) transmitted pressure setpoint and / or flow rate setpoint, a speed setpoint is determined. Electrohydraulic control arrangement according to Claim 9 or 10 , characterized in that the interface (26) comprises a synchronization signal of a machine cycle.

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