DE102013005774B4 - USE OF A VARIABLE SPEED HYDRAULIC PUMP DRIVEN BY A MOTOR AS A HYDROSTATIC TRANSMISSION - Google Patents

Abstract

Control device (30) for controlling a variable-speed hydraulic pump (20) driven by a motor (10), with an adapter (35) for adapting the speed (n) and the stroke volume (Vh) of the hydraulic pump (20), in order to create an electrohydraulic transmission to realize.

Description

The present invention relates to a control device and a control method for controlling a variable-speed hydraulic pump driven by a motor, the motor-pump assembly being used as a hydrostatic transmission with a variable and adaptively tracked transmission ratio. The transmission ratio is defined depending on the operating point and optimization target, in particular dynamics, energy efficiency, etc., and is automatically set by the system.

Variable-speed hydraulic machines are used in many areas of technology. As a rule, high positioning accuracy of the hydraulic machine and minimal energy consumption are required here. DE 10 2011 010 218 A1 shows a method for regulating the pressure of a fluid conveyed by means of a speed-regulated pump, in particular a servo pump, and an electrohydraulic drive system. DE 10 2007 007 005 A1 shows an electrohydraulic control arrangement for controlling a hydraulic consumer. DE 10 2005 012 586 A1 shows an electrohydraulic transmission control device with which shift elements of a transmission can be controlled with the control pressure required to represent a required operating state of the transmission. DE 696 12 072 T2 shows a control system for the torque of a pump, which can be used in a hydraulic work vehicle. DE 199 30 648 A1 shows an electro-hydraulic pressure supply with an adjustable pump and controllable electric drive. EP 2 199 623 A2 shows a hydraulic system for use in agricultural machinery.

In addition, especially in quiet working environments, there is often a low level of noise generated by the hydraulic machine, so that the noise pollution for the environment is kept as low as possible.

The problem here is if, with reduced motor dynamics, sufficient dynamics are to be achieved in the hydraulic system that is driven by the motor. In particular, the dynamics in such a case in the upper power range of a conventional hydraulic machine are not yet sufficient.

At present, a hydraulic accumulator or hydraulic accumulator is often required in this context in some hydraulic machines. On the one hand, this makes the hydraulic machine more expensive and, in addition, has a not insignificant influence on the amount of energy consumed by the hydraulic machine.

It is therefore the object of the present invention to provide a regulating device and a regulating method for regulating a hydraulic pump which is driven by a motor and which is variable in speed, with which the aforementioned problems can be solved. In particular, a control device and a control method for controlling a variable-speed hydraulic pump driven by a motor are to be provided, in which the energy losses and noise from the hydraulic pump and motor can be reduced cost-effectively and an increase in dynamics can be achieved, especially in the upper performance range.

This object is achieved by a control device for controlling a variable-speed hydraulic pump driven by a motor according to patent claim 1.

Advantageous further refinements of the device are specified in the dependent claims.

The object is also achieved by a hydraulic machine according to claim 9, wherein the control device described in the claims can be part of the hydraulic machine, which also includes a hydraulic pump for driving a motor. The motor can in particular be an electric motor that is controlled by a frequency converter or servo drive controller.

The object is also achieved by a control method for controlling a variable-speed hydraulic pump driven by a motor according to patent claim 10.

• • Mehrgrößenregelung: Dynamische Anpassung der Drehzahl und des Pumpen-Hubvolumens (Schwenkwinkel) im Regelungsbetrieb
• • Leistungsanpassung: stationäre Anpassung der Drehzahl und des Pumpen-Hubvolumens (Schwenkwinkel) zur Leistungsanpassung und Systemoptimierung

With the control device described in the claims and the control method described in the claims, in a variable-speed hydraulic pump, not only the speed is used as a manipulated variable for the pressure control of the hydraulic pump, but also the stroke volume of the connected hydraulic pump is changed, so that two manipulated variables for dynamics and performance adjustment are used System has. The following basic principles are distinguished:

• • Multi-variable control: Dynamic adaptation of the speed and the pump stroke volume (swivel angle) in control mode
• • Performance adjustment: stationary adjustment of the speed and the pump stroke volume (swivel angle) for performance adjustment and system optimization

The control device described in the claims and the control method described in the claims are each in the Ability to reduce the speed of the motor or the pump stroke volume (swivel angle) if the power requirement in the hydraulic system is low. This is particularly useful with long pressure holding times or when the hydraulic machine is at a standstill.

It is also possible to reduce the energy losses and noise of the hydraulic pump and the motor at a lower speed in partial load operation. Partial load operation is understood to mean operation of the hydraulic machine in which the power of the motor is reduced in the pressure holding operation of the hydraulic pump, that is to say only a low hydraulic output power is required. In this case, in partial load operation, the actual speed and the swivel angle can be adjusted according to a control law and using a motor-pump model.

Further possible implementations of the invention also include combinations, not explicitly mentioned, of features or embodiments described above or below with regard to the exemplary embodiments.

The person skilled in the art will also add individual aspects as improvements or additions to the respective basic form of the invention.

• 1 ein Blockschaltbild einer Hydraulikmaschine mit einer Regelvorrichtung gemäß einem ersten Ausführungsbeispiel; und
• 2 ein Zeitverlaufdiagramm von Zustandsgrößen der Hydraulikmaschine gemäß dem ersten Ausführungsbeispiel.

The invention is described in more detail below with reference to the accompanying drawings and using exemplary embodiments. Show it:

• 1 a block diagram of a hydraulic machine with a control device according to a first embodiment; and
• 2 a timing diagram of state quantities of the hydraulic machine according to the first embodiment.

In the figures, elements that are the same or have the same function are provided with the same reference symbols, unless otherwise specified.

1 shows a hydraulic machine 1 with an engine 10 , a variable-speed hydraulic pump 20th , a control device 30th and an amplifier 40 . The motor 10 drives the hydraulic pump 20th on, the hydraulic pump 20th from the control device 30th is regulated. The amplifier finds both control 40 Use.

The motor 10 is in particular an electric motor. The motor 10 is with the hydraulic pump 20th via a drive shaft 11 coupled. The motor 10 rotates the drive shaft 11 with an actual speed or actual speed n _IST . The actual speed n _IST can with a speed sensor 12 or it is estimated in encoderless operation with a motor model based on the measured current actual values. The measurement result, i.e. the actual speed n _IST , is entered in the control device 30th entered.

The hydraulic pump 20th can drive a load, for example in the form of an injection mold, a press, a ram, a lifting platform, etc. The hydraulic pump 20th has a swivel disc 21st with the help of an adjustment device 22nd , such as a proportional valve, etc., is pivotable by an adjustable pivot angle α. By pivoting the swivel plate 21st is the volume flow Q and the pressure p of a hydraulic medium of the hydraulic pump 20th adjustable. The hydraulic medium can be hydraulic oil, etc., for example. With a swivel angle sensor 23 can be the actual swivel angle or actual swivel angle α _{IST of} the swivel plate 21st are recorded. The swivel angle sensor 23 is in 1 only hinted at. Alternatively, in a system with a pressure sensor and a synchronous motor, the swivel angle α can also be determined on the basis of the measured values using a model calculation. With a pressure sensor 24 can be the actual pressure or actual pressure p _{IST of} the hydraulic medium of the hydraulic pump 20th are recorded.

The control device 30th has three entrances 31 , 32 , 33 for electrical signals. The entrances 31 , 32 , can also be referred to as analog inputs. In addition, the control device has 30th an exit 34 for an analog electrical signal. The exit 34 can also be referred to as an analog output. The control device 30th also has at each of the entrances 31 , 32 and if necessary at the entrance 33 an analog / digital converter A / D. At the exit 34 has the control device 30th a digital / analog converter D / A. This allows the control device 30th the signals each digitally with an adapter 35 process, as described later in greater detail.

More precisely, the control device has 30th an actual swivel angle analog input 31 in which the swivel angle sensor 23 recorded actual swivel angle α _{IST of} the swivel disk 21st the hydraulic pump 20th is entered. In addition, the control device has 30th an actual pressure analog input 32 in which the pressure sensor 24 recorded actual pressure p _{IST of} the hydraulic medium of the hydraulic pump 10 is entered. In an actual speed input 33 the control device 30th becomes that of the speed sensor 14th recorded actual swivel angle α _{IST of} the swivel disk 11 the hydraulic pump 10 entered. From a target swivel angle analog output 34 gives the control device 30th a nominal swivel angle α _{SOLL of} the swivel plate 11 the hydraulic pump 10 out.

How out 1 can be seen, the _target swivel angle α _{SOLL of} the swivel plate 11 the hydraulic pump 20th in the form of an analog electrical signal into the amplifier 40 entered. The amplifier 40 in turn outputs an adjustment value x _IST , in particular in the form of a voltage U _AUS , etc., to the adjustment device 22nd out. Because of this, the adjusting device 22nd the swivel disk 11 the hydraulic pump 10 _Pivot or adjust according to the specified _target pivot angle α _SOLL . As a result, an actual adjustment value, in particular in the form of an actual voltage U _IST , etc., of the adjustment device 22nd back to the amplifier 40 are fed.

2 shows a diagram of the curves of the actual pressure p _IST , the volume flow Q _pump , the displacement volume V _pump , and the torque M _{pump of} the hydraulic pump 20th in a pressure holding operation of the hydraulic machine 1 of 1 over time t. In the pressure holding operation, the actual pressure p _{IST is} constant. Here are to the left of the line 50 in 2 the curves of the actual pressure p _IST , the volume flow Q _pump , the displacement volume V _pump , and the torque M _{pump of} the hydraulic pump 20th with a standard operation of the hydraulic machine 1 of 1 shown, so if the control device 30th not working. Right of the line 50 in 2 are the curves of the actual pressure p _IST , the volume flow Q _pump , the displacement volume V _pump , and the torque M _{pump of} the hydraulic pump 20th at a target operation of the hydraulic machine 1 of 1 shown, which operation in a control with the control device 30th is achieved.

With the hydraulic machine 1 the pressure control and volume flow control of the hydraulic pump takes place 20th with the control device 30th , especially with their adapter 35 , by adjusting the swivel angle α. In partial load operation of the hydraulic machine 1 , which corresponds to a reduced power in pressure holding operation, becomes the speed n of the motor 10 with the control device 30th customized. This eliminates losses in the hydraulic machine system 1 minimized as well as the torque M of the motor 10 lowered to hold the pressure p. Thus, with the variable-speed hydraulic pump 20th not only the speed n as a manipulated variable for the pressure control of the hydraulic pump 20th but also uses the stroke volume of the hydraulic pump 20th changed.

The adapter 35 is designed in particular in the regulated operation of the hydraulic pump 20th the swivel angle α and the engine speed n to adjust the pressure, force or position control of a cylinder by the hydraulic machine 1 is operated

In the first exemplary embodiment, the pivot angle α is adjusted with the aid of the adjustment device 35 in sections. Here, in a “pressure build-up” section, the swivel angle α is controlled as a function of the pressure by the torque M of the motor 10 to drive consistently at the maximum possible. In a “hold pressure” section, the swivel angle α is reduced to a minimum value by the torque M of the motor 10 to minimize. The "Pressure build-up" section corresponds to a pressure build-up operation of the hydraulic machine 1 . The “Pressure hold” section corresponds to the pressure hold mode of the hydraulic machine 1 .

in welcher α für den Ist-Schwenkwinkel α_IST steht, M_Pumpe für das Drehmoment der Hydraulikpumpe 20 steht, n für die Drehzahl der Antriebswelle 11 steht, p für den Druck steht, und V_h für das maximale Verdrängungsvolumen der Hydraulikpumpe 20 bei α = 100% steht.The actual swivel angle α act _can also be calculated without a sensor according to the following equation (1) on the basis of existing measured values: $$\alpha =\frac{{\mathrm{M.}}_{Pumpe}\cdot 2\mathrm{\Pi }\cdot n}{p\cdot V_H}$$

in which α stands for the actual swivel angle α _IST , M _pump for the torque of the hydraulic pump 20th stands, n is the speed of the drive shaft 11 stands, p stands for the pressure, and V _{h stands} for the maximum displacement of the hydraulic pump 20th at α = 100%.

In the pressure holding mode, the torque M _{pump of} the hydraulic _{pump is} calculated 20th by converting the equation (1) into the following equation (2) $${\mathrm{M.}}_{Pumpe}=\frac{p\ast \alpha \cdot V_H}{2\mathrm{\Pi }n}$$

wobei nmot der Drehzahl n_IST des Motors 10 entspricht und V_pumpe gleich V_h gilt. Die Drehzahl n_mot oder n_IST würde in dem Fall konstant bleiben und erst im Teillastbetrieb angepasst werden.Thus, the swivel angle α is controlled via the analog output 34 the swivel angle setpoint α _SOLL to the hydraulic pump 20th and thus the volume flow Q of the hydraulic pump 20th regulated, which can also be referred to as Q _pump . The volume flow Q _{pump is} calculated from $$Q_{Pumpe}=n_{mOt}\cdot \alpha \cdot V_{pumpe}$$

where nmot is the engine speed n _IST 10 and V _{pump is} equal to V _h . In this case, the speed n _mot or n _IST would remain constant and only be adjusted in partial load operation.

With the previously described method of calculating the current swivel angle α on the basis of the existing measured variables, one can speak of sensorless control.

The section-wise adaptation of the pump stroke volume V _h described above variable speed hydraulic pump 20th forms a 2-point controller with which a stationary adjustment of the pump stroke volume V _{h of} the variable-speed hydraulic pump 20th by adjusting the swivel angle α of the hydraulic pump 20th he follows.

With the control device 30th decreases in the hydraulic machine 1 of 1 the required torque of the motor 10 . This also reduces engine losses in partial load operation. As a result, the hydraulic machine 1 higher energy efficiency. In addition, there is an increase in dynamics in the upper performance range. For the engine 10 is therefore only a standard motor with less power than a hydraulic machine without the described control with the control device 30th required. This can reduce the cost of the hydraulic machine 1 can be kept low according to this embodiment, because you the engine 10 and drive controller, i.e. the control device 30th , can be designed smaller in many applications. Switching between the minimum and maximum stroke volume of the hydraulic pump 20th takes place automatically depending on the required hydraulic power. In the case of low hydraulic power, that is to say a low pump speed, the minimum stroke volume is used and, in the case of high power, the maximum stroke volume is used.

• • Druckregelabweichung > dp_max → maximales Hubvolumen aktiv
• • Druckregelabweichung ≤ dp_max → minimales Hubvolumen aktiv

With the hydraulic machine 1 the pressure control deviation dp or the actual speed n _{IST of} the hydraulic pump is used as the switchover criterion in pressure control 20th used. If dp_max is the maximum pressure regulation deviation, then applies

• • Pressure regulation deviation> dp_max → maximum stroke volume active
• • Pressure regulation deviation ≤ dp_max → minimum stroke volume active

According to a second exemplary embodiment, the variable-speed hydraulic pump 20th the pump stroke volume V _h in the regulated operation of the hydraulic machine 1 of 1 with the help of the adapter 35 dynamically adjusted. In this exemplary embodiment, multivariable control is thus achieved by dynamically adapting the pivot angle α of the hydraulic pump 20th and speed n of the motor 10 executed in regular operation. One advantage of such a control, compared to the prior art, lies in a higher control dynamic due to rapid swivel angle adjustment at the same time as a speed adjustment that is possible in parallel, whereby a higher volume flow change dQ / dt is possible. This is especially the case with large powers and therefore a large engine 10 advantageous.

Otherwise the hydraulic machine is 1 according to this embodiment is constructed in the same way as described with respect to the first embodiment.

1. A) Schaltgetriebe mit zwei verschiedenen Schaltstufen (minimales und maximales Pumpenhubvolumen)
2. B) als stufenloses Automatikgetriebe mit stetiger Anpassung der Übersetzung.

The control device described in the first and second embodiments 30th is used to control one of a motor 10 driven variable speed hydraulic pump 20th and comprises an adapter 35 to adjust the speed n and the stroke volume V _{h of} the hydraulic pump 20th in order to realize an electro-hydraulic transmission for which, for example, the two versions described above are possible

1. A) Gearbox with two different switching stages (minimum and maximum pump stroke volume)
2. B) as a continuously variable automatic transmission with constant adjustment of the translation.

According to a third exemplary embodiment, it is also possible that the input 34 the control device 30th Not applicable if the actual swivel angle α _{IST of} the swivel disk is entered 11 the hydraulic pump 10 into the control device 30th is not required. In this case, the swivel angle sensor can also 23 omitted. This also means that the swivel angle sensor is not connected 23 to the control device 30th . This allows the control device 30th can be realized even more cost-effectively. Otherwise, the second embodiment is constructed in the same way as the first embodiment.

In summary, in the embodiments described above, a control device 30th and a control method for controlling one of an engine 10 driven hydraulic pump 20th provided. The control device 30th comprises an adapter 35 to adjust the speed n and the stroke volume V _{h of} the hydraulic pump 20th for pressure control of the hydraulic pump 20th or for force control or position control of a hydraulic cylinder, which is not shown, and in particular with the hydraulic machine 1 is actuated. Here, the stroke volume V _{h of} the hydraulic pump 20th either stationary by adjusting the swivel angle α of the hydraulic pump 20th or dynamically in controlled operation by dynamically adapting the swivel angle α of the hydraulic pump 20th and the speed n of the motor 10 can be adjusted in regular operation. The unit consists of a hydraulic pump 20th , Engine 10 and drive controller or control device 30th is used as an electro-hydraulic gear to optimize the system efficiency.

All the previously described configurations of the hydraulic machine 1 with their control device 30th and their control method can be used individually or in all possible combinations. In particular, all of the features and / or functions of the exemplary embodiments described above can be combined as desired. In addition, the following modifications in particular are conceivable.

The parts shown in the figures are shown schematically and may differ in the exact configuration from the forms shown in the figures, as long as their functions described above are guaranteed.

By connecting the control device 30th With a standard frequency converter a dynamic and economical solution for controlling the oil quantity and pressure of the hydraulic machine can be achieved 1 , especially the hydraulic pump 20th can be achieved. The control device 30th can in particular be arranged in a servo drive or frequency converter.

Identical mechanical and electrical interfaces, in particular a data bus interface (bus interface), of the hydraulic machine 1 allow the replacement of different units from one manufacturer.

Claims (10)

Control device (30) for controlling a variable-speed hydraulic pump (20) driven by a motor (10), with an adapter (35) for adapting the speed (n) and the stroke volume (Vh) of the hydraulic pump (20), in order to create an electrohydraulic transmission to realize. Control device according to Claim 1 , wherein the adaptation device (35) for adapting a swivel angle (α) of the hydraulic pump (20) on the basis of a measured actual speed (n _IST ) of the motor (10), a measured actual torque (M _IST ) of the hydraulic pump (20 ) and a measured actual pressure (p _IST ) of the hydraulic pump (20) is designed, and wherein the adapter (35) is designed in the controlled operation of the hydraulic pump (20) the pivot angle (α) and the engine speed (n) for pressure - Adjust the force or position control of a cylinder. Control device according to Claim 2 , wherein the adapter (35) is designed to lower the swivel angle (α) to a minimum value in the pressure holding operation of the hydraulic pump (20) in order to minimize the actual torque (M _IST ) of the motor (10) and thus the system losses. Control device according to one of the Claims 1 to 3 , wherein the adapter (35) is designed to calculate the swivel angle (α) as a function of pressure in a pressure build-up mode of the hydraulic pump (20) in order to keep the actual torque (M _IST ) of the motor (10) constant at the maximum possible value. Control device according to one of the preceding claims, wherein the adapter (35) is designed to change the swivel angle (α) in a partial load operation, in which the power of the motor (10) is reduced in the pressure holding operation of the hydraulic pump (20), so that the Actual speed and the swivel angle (α) is adjusted according to a control law and based on a motor-pump model. Control device according to one of the preceding claims, wherein the adapter (35) is designed to adapt the stroke volume (V _h ) of the hydraulic pump (20) either in a stationary manner by adjusting the swivel angle (α) of the hydraulic pump (20) or dynamically in controlled operation by dynamic adaptation the swivel angle (α) of the hydraulic pump (20) and the speed (n) of the motor (10) in normal operation. Control device according to Claim 6 , the adaptation device (35) operating as a 2-point controller for the stationary adaptation of the stroke volume (Vh) of the hydraulic pump (20). Control device according to one of the preceding claims, also with an analog output (34) for outputting the swivel angle (α) as an analog signal to the hydraulic pump (20), and / or an actual swivel angle analog input (31) for inputting the actual swivel angle ( α _IST ) as an analog signal from the hydraulic pump (20), and / or an actual pressure analog input (32) for entering the actual pressure (p _IST ) as an analog signal from the hydraulic pump (20), and / or an actual -Speed input (33) for entering the actual speed (n _IST ) as a signal from the hydraulic pump (20) or the driving motor (10). Hydraulic machine (1) with a hydraulic pump (20) which can be driven by a motor (10) and a control device (30) according to one of the preceding claims, wherein the control device (30) is arranged in the servo drive or frequency converter. Control method for controlling a variable-speed hydraulic pump (20) driven by a motor (10), with the steps of adapting, with an adapter (35), the speed (n) and the displacement (Vh) of the hydraulic pump (20) for pressure, force - and position control of a hydraulic system.

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