CN114810706A

CN114810706A - Hydraulic device for an electrified commercial vehicle, control device for a hydraulic device, and method for operating a hydraulic device

Info

Publication number: CN114810706A
Application number: CN202210055380.3A
Authority: CN
Inventors: V·德沃拉克; A·厄萨姆; M·马赫; G·舍勒; Z·斯戴芬; F·泽曼
Original assignee: ZF Friedrichshafen AG
Current assignee: ZF Friedrichshafen AG
Priority date: 2021-01-18
Filing date: 2022-01-18
Publication date: 2022-07-29
Also published as: DE102021200407A1

Abstract

A hydraulic device (100) for an electrified commercial vehicle (105), comprising: a hydraulic pump (125) for providing a first pressure (130), an electric motor (120) for driving the hydraulic pump (125), and a hydraulic system (145). The hydraulic system (145) has a pump interface (140) to the hydraulic pump (125) and a load interface (160) to the load (110). The hydraulic system (145) is configured to provide a load pressure (163) having a first value using the first pressure (130) in a first hydraulic state and to provide the load pressure (163) having a second value using the first pressure (130) in a second hydraulic state. The control device (170) is configured to determine a model function (205) of the hydraulic system (145) associated with the current hydraulic state using the state signal (175) representative of the current hydraulic state, in order to provide a motor signal (185) for controlling the rotational speed of the electric motor (120) using the model function (205).

Description

Hydraulic device for an electrified commercial vehicle, control device for a hydraulic device, and method for operating a hydraulic device

Technical Field

The invention relates to a hydraulic system for a utility vehicle, to a control device for a hydraulic system and to a method for operating a hydraulic system.

Background

The mobile hydraulic system can be constructed in different ways. However, they are basically composed of the same main components. In some applications, the hydraulic pump in the constant flow system always delivers the same maximum volume flow depending on the rotational speed. If both a high pressure and a lower volume flow are required, for example in the case of a slow lifting of a heavy load by means of a loading crane, excess hydraulic liquid is directed back into the tank for this case.

Disclosure of Invention

Against this background, the present invention provides an improved hydraulic device, an improved control device for a hydraulic device and an improved method for operating a hydraulic device according to the independent claims. Advantageous embodiments result from the dependent claims and the following description.

In addition to the cost reduction, the advantage that can be achieved with the proposed solution is also the adaptable application possibilities in electrified commercial vehicles.

The invention relates to a hydraulic device for an electrified utility vehicle. The hydraulic apparatus includes a hydraulic pump for providing a first pressure; an electric motor coupled with the hydraulic pump to drive the hydraulic pump; and a hydraulic system. The hydraulic system has a pump connection for connection to a hydraulic pump and a load connection for connection to a load, wherein the hydraulic system is designed to provide a load pressure having a first value using the first pressure in a first hydraulic state and a load pressure having a second value using the first pressure in a second hydraulic state. Furthermore, the hydraulic apparatus comprises a control device configured to receive a status signal, wherein the status signal represents a current hydraulic status. The control device is configured to determine a model function of the hydraulic system associated with the current hydraulic state using the state signal, in order to provide a motor signal for controlling the rotational speed of the electric motor using the model function.

The commercial vehicle may be, for example, a vehicle for moving a load, such as, for example, a loading crane, wherein the hydraulic device proposed here may be, for example, part of a so-called load-sensing control device. The system may also be referred to as a load pressure reporting system and is capable of identifying what kind of load is present. In general, the flow rate independent of the load pressure can be regulated by a special control block.

In contrast to the regulation of the load sensing system via sensors, valves and additional hydraulic load reporting or electrical signal lines, which can detect the pressure difference present and keep it constant, the hydraulic device proposed here advantageously allows the load and the load pressure or the pressure at the load to be detected in a sensorless manner. For example, the load may be a linear hydraulic cylinder. This adjustment can be carried out by means of software algorithms in the electric Motor and control device, also called electric Motor (E-Motor).

For example, the output pressure at the hydraulic pump can be calculated by known variables of the electric motor, i.e. current and torque. The calculation or determination of torque may be related to the type and control of the electric motor. For example, if a fixed displacement pump is used, the first pressure or volume flow may be proportional to the rotational speed, i.e. the displacement may be constant. The first pressure can thus be calculated via the rotational speed.

The hydraulic pump of the hydraulic system proposed here is connected to the hydraulic system via a pump connection. The hydraulic system is configured to provide a load pressure at a load interface to a load using a first pressure, wherein the load pressure may be related to a hydraulic state of the hydraulic system. For example, in a first hydraulic state, a control valve disposed in the hydraulic system may be opened, e.g., based on a corresponding user input. In the second hydraulic state, the control valve can be closed, for example. In this case, the hydraulic system can have other hydraulic states in addition to the first and second hydraulic states, depending on the complexity of the system used.

The current hydraulic state, which may be, for example, the first hydraulic state or the second hydraulic state or another hydraulic state, may be detected by the control device by means of a corresponding state signal. The control device may use the status signal to determine a model function associated with the current hydraulic state. For example, a first model function may be associated or associable with a first hydraulic state, while a second model function may be associated or associable with a second hydraulic state. Thus, with the aid of the information transmitted via the state signal about the hydraulic state and the predefined model function, it is possible to calculate: which motor power is optimal for the load applied at the load and a corresponding motor signal may be provided to control the rotational speed of the electric motor.

The corresponding model function may be calculated, set or selected using the status signal. Accordingly, model functions associated with different states may be predetermined. The model function may take into account, for example, a valve position, an efficiency or a characteristic curve of a valve of the hydraulic system. Thus, each model function may be a predetermined state-specific hydraulic system model. By modeling the hydraulic system, a sensor for measuring the current load pressure can be omitted. Instead of this, a model function may be used to determine the load pressure.

The hydraulic device proposed here can advantageously be implemented very inexpensively without additional components such as sensors, signals and hydraulic circuits. Furthermore, the system can be run with an inexpensive fixed displacement pump instead of a more expensive variable displacement pump. The system thus provides an inexpensive and variable solution to implement load sensing functions in commercial vehicles with electro-chemical work functions.

According to one embodiment, the control device may be configured to determine a load pressure signal representative of the load pressure using the pressure signal representative of the first pressure and the model function, and to provide the motor signal using the load pressure signal. For example, the first pressure can be calculated from known electric motor information, such as, for example, the current rotational speed, and provided as a corresponding pressure signal. At the same time, the current load pressure can be calculated on the basis of information from the hydraulic system, which information can be provided to the control device by means of the status signal. The pressure difference between the current load pressure and the sought load pressure can advantageously be determined and, if necessary, a change in the rotational speed of the electric motor can be initiated in order to adapt the current load pressure to the sought load pressure. The efficiency of the hydraulic system can thereby be optimized.

According to another embodiment, the hydraulic system may be configured to provide a status signal to the control device. For example, the hydraulic system may be placed in a first hydraulic state, such as with the valve open. The hydraulic system may provide said information in the form of status signals for the control device, for example by means of an implemented electronic unit. This has the advantage that the control device can be provided with information about the state of the hydraulic system directly and without delay.

According to another embodiment, the hydraulic system may comprise an adjustment interface for receiving an adjustment signal and be configured to use the adjustment signal for setting the current hydraulic state, wherein the adjustment signal may represent a signal provided by the user interface. The user interface may be, for example, a human-machine interface, such as a lever or a switch, by means of which a user or a vehicle driver can set a desired hydraulic state. The signals thus provided by the user can be detected, for example, via the control device and forwarded as adjustment signals to the hydraulic system, or can be processed via a separate electronic control unit of the hydraulic system. Thus, the hydraulic settings desired by the user can be advantageously performed, whereby the hydraulic apparatus can optimize the required motor power.

According to a further embodiment, the hydraulic pump can be designed as a fixed displacement pump. The hydraulic system proposed here can be operated with a vertical pump, although other load sensing systems can be operated with variable displacement pumps, for example, so that the first pressure or volume flow generated by the hydraulic pump can be proportional to the rotational speed. Advantageously, cost savings may be achieved by using an inexpensive fixed displacement pump as compared to a more expensive variable displacement pump.

According to a further embodiment, the hydraulic pump may be configured to provide a first volume flow, and the hydraulic system may be configured to provide a load volume flow having a first value using the first volume flow in a first hydraulic state and a second value using the first volume flow in a second hydraulic state. For example, a greater load volume flow can be provided in the first hydraulic state than in the second hydraulic state, wherein the load volume flow can advantageously be optimized in each case for a load provided at the load.

According to a further embodiment, the control unit can be configured to provide the motor signal for reducing the rotational speed to a minimum value using a status signal, wherein the status signal represents a standstill state as the current hydraulic state. Additionally or alternatively, the speed reduction may also be performed in response to a pressure signal. Thus, if it is desired to maintain a maximum pressure in the system, wherein at the same time no movement should be carried out, the software can run the electric motor at a minimum rotational speed and additionally or alternatively also switch off the electric motor, in order to thereby advantageously save energy. The input to the software may be the output pressure, i.e. the torque of the electric motor, or may be a signal from the hydraulic system, such as for example the position of a directional valve.

According to another embodiment, the control device may be configured to receive a load signal representative of a load acting on the load, so as to provide the motor signal using the load signal. For example, in some applications, a description is provided regarding the load. In these cases, the information may be used to calculate the hydraulic pressure or the load pressure. The calculation may be related to the type of load. For example, if sufficient detailed specifications about the load are available, a "feed forward" control may be used. All information can be transferred to the software. The control device can receive information about the load and thus achieve an optimized regulation or synchronization of, for example, the directional control valves. Response times can thereby advantageously be significantly improved.

According to another embodiment, the control device may comprise a reference table (nachschalagetabelle) for selecting the model function. For example, a respective predefined model function may be associated with each predefined hydraulic condition in a reference table. This has the following advantages: time and energy can be saved when processing the information obtained from the hydraulic system and when subsequently providing the motor signal.

The hydraulic system may be configured to determine the status signal using a temperature value indicative of an oil temperature of the hydraulic system. Thereby, the model function may more accurately reflect the current state of the hydraulic system.

According to a further embodiment, the hydraulic device may have a rotational speed sensor for providing a rotational speed signal representing a rotational speed of the electric motor, wherein the control device may be configured to provide the motor signal using the rotational speed signal. For example, if the load at the hydraulic cylinder of the load is increased, the pressure in the hydraulic system will also increase, thereby reducing the rotational speed of the pump. In this case, the current torque is too small for the applied load. A rotational speed sensor at the electric motor may provide information about the rotational speed in the form of a rotational speed signal. The control device can be designed to provide the motor signal using the rotational speed signal, whereby the rotational speed of the electric motor can be increased, for example. Accordingly, when the load at the load drops, the rotational speed at the electric motor is increased, i.e. excess power is taken, so that the control device can use the rotational speed signal to cause the current to drop. Hereby, a desired constant rotational speed can advantageously be achieved irrespective of load and use, whereby the system can achieve a higher efficiency.

According to another embodiment, the hydraulic apparatus may have a frequency converter configured to receive the motor signal and to use the motor signal to control a rotational speed of the electric motor. For example, a frequency converter, which may also be referred to as an inverter, may receive the motor signal from the control device and control the rotational speed accordingly. Advantageously, motor control can be optimized and energy can be saved by means of the frequency converter.

According to another embodiment, the frequency converter may be configured to operate a further electric motor. For example, the further electric motor may be coupled to a further hydraulic pump for providing the further first pressure, wherein the further hydraulic pump may be coupled to the further hydraulic system via a further pump interface. The further hydraulic system may have a further load connection for connection to a further load and be designed to provide a further load pressure having a first value using the further first pressure in a further first hydraulic state and to provide a further load pressure having a second value using the further first pressure in a further second hydraulic state. Furthermore, the control device may be configured to receive a further status signal provided by a further hydraulic system, wherein the further status signal may represent a further current hydraulic status. The control device may be configured to use the further state signal to determine a further model function of the further hydraulic system associated with a further current hydraulic state, in order to use the further model function to provide a further motor signal for controlling the rotational speed of the further electric motor to the frequency converter. Advantageously, therefore, one frequency converter can advantageously be used for a plurality of electric motors and thus for a plurality of loads with different loads.

Furthermore, a control device for a hydraulic system is proposed, wherein the hydraulic system has: a hydraulic pump for providing a first pressure; and an electric motor coupled with the hydraulic pump to drive the hydraulic pump; and a hydraulic system having a pump interface for connection with the hydraulic pump and a load interface for connection with a load. The hydraulic system is configured to provide a load pressure having a first value in a first hydraulic state using the first pressure and to provide a load pressure having a second value in a second hydraulic state using the first pressure. The control device is configured to receive a status signal, wherein the status signal is representative of a current hydraulic state of the hydraulic system. Furthermore, the control device is configured to determine a model function of the hydraulic system associated with the current hydraulic state using the state signal, in order to provide a motor signal for controlling the rotational speed of the electric motor using the model function. Advantageously, the control device proposed here can be used to optimize a hydraulic system, in particular of a commercial vehicle, and to adapt the respective load currently applied to the load.

Furthermore, a method for operating a hydraulic system is proposed, which has: a hydraulic pump for providing a first pressure; an electric motor coupled with the hydraulic pump to drive the hydraulic pump; and a hydraulic system. The hydraulic system comprises a pump connection for connection to a hydraulic pump and a load connection for connection to a load, and is designed to provide a load pressure having a first value using the first pressure in a first hydraulic state and a load pressure having a second value using the first pressure in a second hydraulic state. The method comprises the following steps: receiving, by the control device, a status signal, wherein the status signal represents a current hydraulic state of the hydraulic system, using the status signal to determine a model function of the hydraulic system associated with the current hydraulic state. Furthermore, the method comprises the steps of: a motor signal for controlling the rotational speed of the electric motor is provided using a model function.

Drawings

The invention is explained in more detail exemplarily with reference to the drawings. The figures show:

FIG. 1 is a schematic illustration of a hydraulic apparatus according to an embodiment;

FIG. 2 is a schematic diagram of a control device according to an embodiment;

FIG. 3 is a schematic diagram of a hydraulic apparatus according to an embodiment;

FIG. 4 is a schematic illustration of a hydraulic apparatus according to an embodiment;

FIG. 5 is a schematic illustration of a hydraulic apparatus according to an embodiment; and

FIG. 6 is a block diagram of an embodiment of a method for operating a hydraulic device.

In the following description of the preferred embodiments of the present invention, the same or similar reference numerals are used for elements shown in the respective drawings and functioning similarly, wherein repeated description of the elements is omitted.

Detailed Description

FIG. 1 shows a schematic diagram of a hydraulic apparatus 100 according to an embodiment. In the embodiment described, the hydraulic device 100 is arranged in an electric utility vehicle 105, which comprises, by way of example only, a loading crane (Ladekran). The commercial vehicle 105 comprises a hydraulic consumer 110, which is configured merely as a linear hydraulic cylinder by way of example. For example, in operation, load 115 acts on load 110. The load 110 is used, for example, to hold or move a load 115.

The working movement of a load crane or similar load of a commercial vehicle is characterized by a movement sequence from very fast to very slow in the case of different loads. To this end, the hydraulic system 100 shown here serves to automatically adapt to load changes and ensure a constant operating speed of the commercial vehicle 105 by reacting precisely to operator presets, and thus a comfortable operation of the system. Here, the hydraulic system 100 comprises an electric motor 120, which is coupled to a hydraulic pump 125 for driving the latter. The hydraulic pump 125 in the exemplary embodiment is, for example only, a fixed displacement pump for providing a first pressure 130, which is also designated by p1, and for example only a first volume flow 135, which is also designated by Q1, in the hydraulic system 100.

The hydraulic pump 125 is connected to a hydraulic system 145 via a pump interface 140. Various control valves 146, control blocks 147, connecting lines 148 and further valves 149 are provided in the hydraulic system 145 merely by way of example. These components of the hydraulic system 145 may be adjusted such that the hydraulic system 145 may have a first hydraulic state and a second hydraulic state. To this end, the hydraulic system 145 in the described embodiment comprises a regulation interface 150 for receiving a regulation signal 153 and is configured to set the current hydraulic state by using the regulation signal. Here, the adjustment signal 153 represents, by way of example only, a signal 158 provided by the user interface 155. The first hydraulic state corresponds, for example only, to a state with the control valve 146 opened by the user, while the second hydraulic state corresponds to a state with the control valve 146 closed. In the depicted embodiment, the hydraulic system 145 is configured to provide a load pressure 163 and a load volume flow 165 via the load interface 160 using the first pressure 130 and the first volume flow 135 in the first hydraulic state. Here, the load pressure 163 and the load volume flow 165 each have a first value corresponding to a first hydraulic state. Likewise, the hydraulic system 145 is configured to provide a load pressure 163 and a load volume flow 165, each having a second value in the exemplary embodiment, which is lower than the first value as a result of the closing of the control valve 146 in the second hydraulic state, via the load connection 160 using the first pressure 130 and the first volume flow 135 in the second hydraulic state. The load 110 and thus the load 115 applied at the load 110 can be moved by means of the load pressure 163 and the load volume flow 165.

In order to achieve automatic load adaptation of the electric motor 120 when the load 115 changes, the hydraulic apparatus 100 shown here further comprises a control device 170 which is configured to receive a status signal 175 representing the current hydraulic state. The status signal 175 may be provided by the hydraulic system 145, for example only, where the current hydraulic state corresponds to either the first hydraulic state or the second hydraulic state. The control device 170 is configured to use the status signal 175 to determine a model function of the hydraulic system 145 that is associated with the current hydraulic state. Furthermore, the hydraulic apparatus 100 in the embodiment comprises a rotational speed sensor 180 configured to detect a current rotational speed of the electric motor 120 and to provide a rotational speed signal 183 representing the rotational speed to the control device 170.

The control device 170 is only exemplarily configured to provide a motor signal 185 for controlling the rotational speed of the electric motor 120 using the model function and the rotational speed signal 183. Here, in the described embodiment, the hydraulic device 100 comprises a frequency converter 190 for receiving the motor signal 185, wherein the frequency converter 190 is configured merely as an example to control the rotational speed of the electric motor 120 using the motor signal 185.

In other words, the hydraulic system 100 shown here makes it possible to determine the pressure and the volume flow at the load 115 and the load 110 without sensors or to determine the flow rate and the oil pressure downstream of the hydraulic pump 125. In the described embodiment, this problem is achieved by means of software algorithms in the electronic components, i.e. the electric motor 120 and the frequency converter 190 and the control device 120. The first pressure 130 or output pressure at the hydraulic pump 125 can be calculated from known variables, i.e., the current and torque of the electric motor 120. The calculation or determination of the torque is related to the type and control of the electric motor 120. Since in the exemplary embodiment a fixed displacement pump is used, the first volume flow 135 is proportional to the rotational speed, i.e. the displacement is constant, so that the first volume flow 135 can be calculated via the rotational speed. For accurate volumetric flow values, a curve of the volumetric efficiency of the pump is required. To calculate the pressure at load 110, a description of hydraulic system 145 and the included components is necessary. For software-based calculations, information such as pressure losses, component efficiencies and characteristic curves of the

valves

146, 149 are required and are taken into account in the model function according to one embodiment, wherein the characteristic curves relate to pressure, volume flow, oil temperature, etc. Accordingly, the model function may represent a model of the hydraulic system 145 in a particular state. Thus, the pressure difference to be applied between the first pressure 130 and the load pressure 163 may be calculated, and the software of the control device 170 regulates the demand-optimized supply to the load 110 according to the formula Q2, p2 — Q1, p1 functions (T, p, T, Q, η). Here, the function (T, p, T, Q, η) may represent a corresponding model function. Here, the parameters T, p, T, Q, η may define the current state of the hydraulic system 145. According to one embodiment, at least some of the parameters are transmitted via status signals 175. According to one exemplary embodiment, the parameter is detected using a suitable sensor device, for example using a timer for detecting the time T, a pressure sensor for detecting the pressure p, a temperature sensor for detecting the temperature T, a flow rate sensor for detecting the volume flow Q and/or a rotational speed sensor for detecting the rotational speed η.

Fig. 2 shows a schematic diagram of a control device 170 according to an embodiment. The control device 170 shown here corresponds to or is similar to the control device described earlier in fig. 1. The control device 170 is configured to receive a status signal 175 that is representative of the current hydraulic state of the hydraulic system previously described in fig. 1.

The control device 170 comprises, by way of example only, a reference table 200, by means of which the respective model function 205 can be associated with the current hydraulic state using the state signal 175. Alternatively, for example, a model function is calculated or otherwise determined using the status signal 175.

Further, the control device 170 in the depicted embodiment is configured to receive a pressure signal 210 representative of the first pressure and determine a load pressure signal 215 representative of the load pressure using the pressure signal 210 and the model function 205. Here, in the embodiment, the load pressure signal 215 corresponds to the calculated value of the load pressure described in fig. 1.

In the exemplary embodiment, pressure signal 210 represents, by way of example only, a first pressure which requires a reduction of the rotational speed of the electric motor described above in fig. 1 to a minimum value in order to produce a standstill of the hydraulic system. In another embodiment, the state signal 175 can also represent the current hydraulic state as a standstill state and thus likewise require a reduction in the rotational speed. In other words, in the described embodiment, it is required to maintain a maximum pressure in the system and at the same time not to perform any movement. Accordingly, the software of the control device 170 is used to run the electric motor at a minimum rotational speed to thereby save energy. Optionally alternatively, the electric motor is also switched off in the stationary state.

In one embodiment, the control device 170 is additionally configured to receive a load signal 220 that is representative of a load acting on the load. The load pressure signal 215 and the load signal 220 may be used to provide the motor signal 185, wherein the rotational speed of the electric motor described in the previous fig. 1 may be controlled in response to the motor signal 185.

Fig. 3 shows a schematic diagram of a hydraulic device 100 according to an embodiment. The hydraulic apparatus 100 shown here corresponds to or is similar to the hydraulic apparatus described in fig. 1. Information about the applied load 115 is provided in the view shown here. In these cases, the information may be used to calculate the hydraulic pressure p2 or the load pressure depicted in fig. 1. The calculations are related to the type of load 110. If sufficient detail regarding the load 115 is available, a "feed forward" control may be used. All information can be transferred to the software of the control device 170. The control device 170 is configured to receive user desired settings and information about the load 115 from the user interface 155, thus enabling optimized adjustment or synchronization of the directional valves in the hydraulic system 145.

Fig. 4 shows a schematic diagram of a hydraulic device 100 according to an embodiment. The hydraulic apparatus 100 shown here corresponds to or is similar to the hydraulic apparatus described in the previous fig. 1 and 3, with the difference that: in the illustrated embodiment, the frequency converter 190 is configured to operate a further electric motor 400 in addition to the electric motor 120. In this case, the further electric motor 400 is coupled, similarly to the electric motor 120, to a further hydraulic pump 405 in order to drive a further load 410 via a hydraulic system as already described in fig. 1. In the exemplary embodiment, the frequency converter 190 can be actuated as described in fig. 1 by a control device 170, which is in turn coupled to the user interface 155.

Fig. 5 shows a schematic diagram of a hydraulic device 100 according to an embodiment. The hydraulic apparatus 100 shown here corresponds to or is similar to the hydraulic apparatus described in the previous fig. 1, 3 and 4, with the difference that: in the exemplary embodiment, hydraulic system 100 has an additional frequency converter 500 in addition to frequency converter 190. In the depicted embodiment, the additional frequency converter 500 controls an additional electric motor 505 that is coupled to an additional hydraulic pump 510 that drives an additional load 515 via a hydraulic system as depicted in fig. 1. In this case, in the exemplary embodiment, the additional frequency converter 500 can be controlled, in a manner equivalent to the frequency converter 190, by a control device 170, which is in turn coupled to the user interface 155.

Fig. 6 shows a block diagram of an embodiment of a method 600 for operating a hydraulic device as described with reference to the preceding figures. Accordingly, the hydraulic system which can be operated by means of the method 600 shown comprises a hydraulic pump, an electric motor for driving the hydraulic pump, and a hydraulic system which is pressurized on the input side via the hydraulic pump and which can output pressure to a load on the output side.

The method 600 includes a step 605 in which a status signal indicative of a current hydraulic state of the hydraulic system is received. In step 610, a model function of the hydraulic system associated with the current hydraulic state is determined using the state signal. Further, the method 600 includes a step 615 of providing a motor signal for controlling a rotational speed of the electric motor using the model function.

List of reference numerals:

100 hydraulic device

105 commercial vehicle

110 load

115 load

120 electric motor

125 hydraulic pump

130 first pressure

135 first volumetric flow

140 pump interface

145 hydraulic system

146 control valve

147 control block

148 connecting line

149 further valves

150 adjustment interface

153 adjusting signal

155 user interface

158 signal

160 load interface

163 load pressure

165 load volume flow

170 control device

175 status signal

180 revolution speed sensor

183 revolution speed signal

185 motor signal

190 frequency converter

200 reference table

205 model function

210 pressure signal

215 load pressure signal

220 load signal

400 additional electric motor

405 additional Hydraulic Pump

410 additional loads

500 additional frequency converter

505 additional electric motor

510 additional hydraulic pump

515 additional load

600 method for operating a hydraulic system

605 receiving step

610 determination step

615 providing step

Claims

1. A hydraulic device (100) for an electrified commercial vehicle (105), wherein the hydraulic device (100) comprises the following features:

a hydraulic pump (125) for providing a first pressure (130);

an electric motor (120) coupled with the hydraulic pump (125) to drive the hydraulic pump (125);

a hydraulic system (145) having a pump interface (140) for connection with the hydraulic pump (125) and a load interface (160) for connection with a load (110), wherein the hydraulic system (145) is configured to provide a load pressure (163) having a first value using the first pressure (130) in a first hydraulic state and a load pressure (163) having a second value using the first pressure (130) in a second hydraulic state; and

a control device (170) configured to receive a status signal (175), wherein the status signal (175) represents a current hydraulic state, and to determine a model function (205) of the hydraulic system (145) associated with the current hydraulic state using the status signal (175) in order to provide a motor signal (185) for controlling a rotational speed of the electric motor (120) using the model function (205).

2. The hydraulic apparatus (100) of claim 1, wherein the control device (170) is configured to determine a load pressure signal (215) representative of the load pressure (163) using the pressure signal (210) representative of the first pressure (130) and the model function (205), and to provide the motor signal (185) using the load pressure signal (215).

3. The hydraulic apparatus (100) of any preceding claim, wherein the hydraulic system (145) is configured to provide the status signal (175) to the control device (170).

4. The hydraulic apparatus (100) of any one of the preceding claims, wherein the hydraulic system (145) comprises an adjustment interface (150) for receiving an adjustment signal (153) and is configured to use the adjustment signal (153) to set the current hydraulic state, wherein the adjustment signal (153) represents a signal (158) provided by a user interface (155).

5. The hydraulic apparatus (100) of any one of the preceding claims, wherein the hydraulic pump (125) is a fixed displacement pump.

6. The hydraulic apparatus (100) of any one of the preceding claims, wherein the hydraulic pump (125) is configured to provide a first volumetric flow (135), and wherein the hydraulic system (145) is configured to provide a load volumetric flow (165) having a first value using the first volumetric flow (135) in a first hydraulic condition and to provide a load volumetric flow (165) having a second value using the first volumetric flow (135) in a second hydraulic condition.

7. The hydraulic apparatus (100) of any one of the preceding claims, wherein the control device (170) is configured to provide the motor signal (185) for reducing the rotational speed to a minimum value using the status signal (175), wherein the status signal represents a stationary state as the current hydraulic state.

8. The hydraulic apparatus (100) of any one of the preceding claims, wherein the control device (170) is configured to receive a load signal (220) representative of a load (115) acting on the load (110) for providing the motor signal (185) using the load signal (220).

9. The hydraulic apparatus (100) of any preceding claim, wherein the hydraulic system (145) is configured to determine the status signal (175) using a temperature value indicative of an oil temperature of the hydraulic system (145).

10. The hydraulic apparatus (100) of any one of the preceding claims, having a rotational speed sensor (180) for providing a rotational speed signal (183) representing a rotational speed of the electric motor (120), wherein the control device (170) is configured to provide the motor signal (185) using the rotational speed signal (183).

11. The hydraulic apparatus (100) of any one of the preceding claims having a frequency converter (190) configured to receive the motor signal (185) and to control a rotational speed of the electric motor (120) using the motor signal (185).

12. The hydraulic apparatus (100) of claim 11, wherein the frequency converter (190) is configured to operate an additional electric motor (400).

13. A control device (170) for a hydraulic apparatus (100) having: a hydraulic pump (125) for providing a first pressure (130); an electric motor (120) coupled with the hydraulic pump (125) to drive the hydraulic pump (125); and a hydraulic system (145) having a pump interface (140) for connection with the hydraulic pump (125) and a load interface (160) for connection with a load (110), wherein the hydraulic system (145) is configured to provide a load pressure (163) having a first value using the first pressure (130) in a first hydraulic state and a load pressure (163) having a second value using the first pressure (130) in a second hydraulic state; wherein the control device (170) is configured to receive a status signal (175), wherein the status signal (175) represents a current hydraulic state of the hydraulic system (145), and wherein the control device is configured to determine a model function (205) of the hydraulic system (145) associated with the current hydraulic state using the status signal (175) in order to provide a motor signal (185) for controlling the rotational speed of the electric motor (120) using the model function (205).

14. A method (600) for operating a hydraulic device (100) having: a hydraulic pump (125) for providing a first pressure (130); an electric motor (120) coupled with the hydraulic pump (125) to drive the hydraulic pump (125); and a hydraulic system (145) having a pump interface (140) for connection with the hydraulic pump (125) and a load interface (160) for connection with a load (110), wherein the hydraulic system (145) is configured to provide a load pressure (163) having a first value using the first pressure (130) in a first hydraulic state and a load pressure (163) having a second value using the first pressure (130) in a second hydraulic state; wherein the method (600) has the steps of:

receiving (605), by a control device (170), a status signal (175), wherein the status signal (175) represents a current hydraulic state of the hydraulic system (145),

determining (610) a model function (205) of the hydraulic system (145) associated with the current hydraulic state using a state signal (175); and

providing (615), using the model function (205), a motor signal (185) for controlling the rotational speed of the electric motor (120).