Hydrostatic drive

Abstract

A hydrostatic drive includes at least one hydrostatic pump configured to supply at least one hydrostatic consumer and an apparatus for an energy recovery procedure of at least a part of the energy that is output by the consumer. An electronic control unit or at least one software component is further included, with which the energy recovery procedure is controlled in a variable manner and depends upon detected influencing variables.

Claims

1. A hydrostatic drive comprising: at least one hydrostatic pump configured to supply at least one hydrostatic consumer with operating fluid; an electric motor configured to drive the hydrostatic drive; an electronic storage device operably connected to the electric motor; a temperature sensor configured to determine a sensed temperature of the operating fluid; and an apparatus configured to recover at least a part of a braking energy or decelerating energy generated by the at least one hydrostatic consumer according to an energy recovery procedure, the apparatus including an electronic control unit configured to control the apparatus in a variable manner and in dependence upon at least one detected influencing variable, the electronic control unit operably connected to the temperature sensor, wherein the at least one detected influencing variable includes the sensed temperature, wherein the energy recovery procedure includes selectively storing the braking energy or the decelerating energy in the electronic storage device when the at least one hydrostatic pump is operated as a motor and when the electric motor is operated as a generator, and wherein the electronic control unit is configured to switch off the energy recovery procedure until the sensed temperature is greater than or equal to an optimal operating temperature of the operating fluid, such that a cold start behavior of the hydrostatic drive is optimized.

2. The hydrostatic drive according to claim 1, further comprising: at least one pressure sensor, wherein the at least one detected influencing variable includes a pressure of the operating fluid or pressures of operating fluids at one or more sites in a drive train of the hydrostatic drive.

3. The hydrostatic drive according to claim 1, wherein the at least one hydrostatic consumer includes a traction motor configured as a pump to generate the braking energy or the decelerating energy.

4. The hydrostatic drive according to claim 1, wherein: the at least one hydrostatic consumer includes work equipment, and the recovered braking energy is generated from mass inertia or from potential energy.

5. The hydrostatic drive according to claim 1, wherein: a first hydrostatic consumer of the least one hydrostatic consumer is configured to generate the braking energy or the decelerating energy, and a second hydrostatic consumer of the at least one hydrostatic consumer is supplied directly with the recovered braking energy or decelerating energy.

Description

BRIEF DESCRIPTION

(1) FIG. 1 illustrates an exemplary embodiment of the hydrostatic drive in accordance with the disclosure;

(2) FIG. 2 illustrates a first strategy for the energy recovery procedure using the hydrostatic drive shown in FIG. 1;

(3) FIG. 3 illustrates a second strategy for the energy recovery procedure using the hydrostatic drive shown in FIG. 1;

(4) FIG. 4 illustrates a third strategy for the energy recovery procedure using the hydrostatic drive shown in FIG. 1.

DETAILED DESCRIPTION

(5) FIG. 1 illustrates an exemplary embodiment of the hydrostatic drive in accordance with the invention that is installed in a mobile work machine (not further illustrated). A hydrostatic pump 2, which has an adjustable or non-adjustable flow volume, for supplying a first consumer 4 and a second consumer 5, and one or more further pumps 6 for other work functions or for auxiliary units are driven by a primary drive 1 that can be a diesel engine or an electric motor. In embodiments having the primary drive 1 configured as an electric motor, the hydrostatic drive further includes an electronic storage device 9. The electronic storage device 9 is operably connected to the primary drive 1.

(6) The pump 2 draws in oil from a tank 8 and conveys it to the consumer 4 by way of a valve block 10 having a restrictor. A temperature sensor 12 is arranged in the tank 8.

(7) An electronic control unit 14 is connected by means of signal lines to the primary drive 1, the pump 2, the valve block 10, the temperature sensor 12 and a sensor arrangement 16. The sensor arrangement 16 comprises in the illustrated exemplary embodiment a position sensor and an apparatus for detecting the surrounding topology (for example a camera). Furthermore, the sensor arrangement 16 can also comprise an acceleration sensor or one of the other sensors mentioned in this document. In particular, the sensor arrangement 16 comprises in the case of the illustrated exemplary embodiment a plurality of pressure sensors that are naturally arranged on components that are influenced by pressure, such as the pump 2, the valve block 10, the consumer 4, the tank 8 or on lines that are arranged between them.

(8) FIG. 2 illustrates a first strategy for the energy recovery procedure using the hydrostatic drive shown in FIG. 1. This strategy takes into consideration the influencing variable ‘temperature of the operating means’ which is detected by means of the temperature sensor 12 in the tank 8. In the case of this strategy, the energy recovery procedure is switched off until the oil is brought to an optimal operating temperature by means of a restriction operation by way of the valve block 10. The cold start behavior of the hydrostatic drive is optimized as a result. The status represents in this case whether an energy recovery procedure is requested or whether on the other hand a restriction operation is performed.

(9) FIG. 3 illustrates a second strategy for the energy recovery procedure based on the hydrostatic drive shown in FIG. 1. The influencing variables ‘ambient topology’ and ‘position’ are taken into consideration. For this purpose, the sensor arrangement 16 has a position sensor and an apparatus for detecting the surrounding topology (for example a camera). The work equipment is lowered and in this case potential energy recovered. The point in time in which the work equipment strikes the ground is predicted prior to the work equipment striking the ground, in other words in advance. The energy recovery procedure can consequently be terminated shortly before said work equipment strikes the ground.

(10) It is consequently possible to initiate in advance necessary switching procedures in the drive train which can involve a very long period of time. As a consequence, a uniform operating behavior is realized. Switching pressures, pressure peaks or interruptions in the traction force are reduced. The mentioned switching procedure can be a full pivot movement or a change in the rotational direction of the pump 2.

(11) FIG. 4 illustrates a third strategy for the energy recovery procedure using the hydrostatic drive shown in FIG. 1. The influencing variables ‘surrounding topology’ and ‘position’ are also taken into consideration in this case. As in the case of the second strategy, the end time point for the energy recovery procedure is predicted, in other words is calculated in advance. Consequently, it is necessary for the drive train to change from the generator mode into the motor mode and output power.

(12) In order to increase the dynamics and response behavior of the drive train after immediately switching over, the primary drive 1 that is embodied as the internal combustion engine is ‘prestressed’ in order to be able to react more quickly to the future load demand. For this purpose, a corresponding status is transmitted to an engine control unit of the internal combustion engine. If the status of the energy recovery procedure changes to the restriction operation, then the rotational speed and the boost pressure of the internal combustion engine are adjusted (for example increased) in preparation.

(13) The disclosure discloses a hydrostatic drive having at least one hydrostatic pump 2 for supplying at least one hydrostatic consumer 4 and said hydrostatic drive having an apparatus for the energy recovery procedure of at least a part of the energy that is output by the consumer. The apparatus comprises an electronic control unit 14 or at least a software component with which the energy recovery procedure can be controlled in a variable manner and in this case depends upon at least one detected influencing variable. For this purpose, the apparatus furthermore comprises at least one sensor 16, a camera or an operating element that detects the influencing variable.

LIST OF REFERENCE NUMERALS

(14) 1 Primary drive 2 Pump 4 Consumer 6 Further pump(s) 8 Tank 10 Valve block 12 Temperature sensor 14 Control unit 16 Sensor arrangement