DE102007018600A1 - Hydraulic / electrical converter - Google Patents

Abstract

Disclosed is a hydraulic / electrical converter with a driven by a natural power pump, via which a hydraulic accumulator is charged and a hydraulic motor is driven. The latter drives a generator to convert the hydraulic energy into electrical energy. According to the invention, the rotational speed of the hydraulic motor is adjusted via a secondary control.

Description

The The invention relates to a hydraulic / electrical converter according to the Preamble of claim 1.

Such converters are used for example in wave generators, as shown in the US 6,300,689 B1 are described. The known wave generator has a hydraulic cylinder, which is in operative connection with a buoy, so that the hydraulic cylinder is actuated by the swell and the corresponding movement of the buoy and pressure medium is conveyed into a hydraulic circuit. The hydraulic cylinder is associated with a hydraulic rectifier, so that regardless of the extension or retraction movement of the hydraulic cylinder pressure medium is conveyed into the hydraulic circuit to charge the hydraulic rectifier downstream hydraulic accumulator and drive a constant motor. The output shaft of this constant-speed motor is connected to a generator, so that the hydraulic energy in the above-described hydraulic circuit is converted into electrical energy. Since the swell greatly varies both in terms of wave height and frequency, a complex electronic circuit for equalizing the generator output voltage must be provided.

In contrast, The invention is based on the object, a hydraulic / electrical converter to create, in which even with strong fluctuations on the hydraulic side a uniform output voltage at the generator is obtained.

These Task is by a hydraulic / electrical converter with the Characteristics of claim 1 solved.

According to the invention the transducer with one of a natural force, such as swell driven pump, via which a hydraulic accumulator rechargeable and a hydraulic motor is driven, in turn, a Generator for converting the hydraulic energy into electrical Energy is driving. According to the invention, the hydraulic motor connected to a pressure network and speed controlled, so that the Generator by adjusting the swivel angle in dependence from the hydraulic side fluctuations to a large extent with a predetermined speed can be driven.

such Systems with a variable speed operated on a pressure network Servo motor are also referred to as secondary control. In these systems, the speed of the variable motor is controlled so that they are independent of the respective load pressure at the Pressure net applied network pressure is achieved. This is essentially depending on the charge state of the hydraulic accumulator. It must the displacement of the hydraulic motor be changed so long until a balance of engine torque with the load (generator) exists and at the same time the target speed is reached.

at the secondary regulation is accordingly a pressure coupling with current response in contrast to conventional Drive systems in which a current coupling with pressure response consists.

According to the invention it is preferred if the speed control performed electro-hydraulically is, wherein the pivot angle of the hydraulic motor via a Adjusting cylinder is adjusted.

in the Pressure medium flow path between the pump and the hydraulic motor is preferably arranged a hydraulic rectifier, so that the hydraulic motor regardless of the actuation direction of Pump can be supplied with pressure medium.

This hydraulic rectifier is preferably designed as a directional control valve, depending on the direction of movement of the pump is switchable.

This Directional control valve is preferably designed with a blocking position, in the interrupted the fluid connection between the pump and hydraulic motor is.

at The control circuit for controlling the hydraulic motor is the speed control underlying a position control of an actuator of the hydraulic motor.

at an advantageous embodiment of the invention is in the pressure network of the hydraulic motor and a low-pressure accumulator arranged so that cavitations can be avoided.

The Pressure network with the hydraulic motor and the pump is preferably as closed circuit executed.

Around Compensate for leakage losses and exchange the pressure medium in the print network, For example, the converter may be equipped with a food purifier be.

The Pump is preferably as one of the swell actuated Hydraulic cylinder executed.

other advantageous developments of the invention are the subject of further Dependent claims.

in the Below is a preferred embodiment of Invention explained in more detail with reference to schematic drawings. Show it:

1 a circuit diagram of a hydraulic / electrical converter according to the invention (wave generator) and

2 a food purifier of the converter 1 ,

According to the in 1 the circuit diagram shown, the illustrated embodiment of a hydraulic / electrical converter consists essentially of a pump 2 , a hydraulic rectifier 4 , one in a print network 6 arranged speed-controlled variable motor 8th , a generator driven by it 10 and a control loop 12 for speed control of the hydraulic motor 8th ,

The pump 2 is as a synchronous cylinder 14 executed, the piston is actuated by the swell. For this operation different models are known. Thus, for example, in the converter described above according to the US 6,300,689 B1 a buoy connected to the piston of a hydraulic cylinder, so that the up and down movement of the buoy caused by the swell is converted into a piston stroke. Such a system can also be found in the in 1 illustrated embodiment used to the piston 16 the synchronous cylinder 14 to press. The two from the piston 16 limited annular spaces of the Gleichzugzylinders 14 are over two pressure lines 18 . 20 with the hydraulic rectifier 4 connected. This is in the illustrated embodiment by a 4/3-way valve 22 executed, which is biased by a spring assembly into its illustrated blocking position in which the pressure medium connection between the pump 2 and the hydraulic motor 8th is interrupted. The two output ports of the directional control valve 22 are connected to the printing network 6 connected. This print network 6 consists essentially of a high-pressure branch 24 and a low pressure branch 26 connected to the high-pressure connection or the low-pressure connection of the hydraulic motor 8th are connected. In the high pressure branch 24 is a high-pressure accumulator 28 and in the low pressure branch 26 a low pressure accumulator 30 provided, over which the pressure in the pressure net 6 can be kept approximately constant and the occurrence of cavitations is prevented.

The adjustment of the directional valve 22 via switching magnets, whereby by switching to the (a) marked switching position, the pressure line 18 with the high pressure branch 24 and the low pressure line 20 with the low pressure branch 26 connected is. When switching to the (b) marked switching position is then corresponding to the pressure line 18 with the low pressure branch 26 and the pressure line 20 with the high pressure branch 24 connected.

Switching the directional control valve 22 takes place in dependence on the direction of movement of the piston 16 , The piston movement is effected by means of a displacement transducer 32 detected and determined by a control unit, the speed of movement of the piston. Switching the directional control valve 22 then takes place in each case in the top and bottom dead center. This can be very easily detected via the displacement transducer and the calculated movement speed of the piston, since it has the speed 0 at the dead center. Switching the directional control valve 22 then takes place in each case such that the decreasing pressure chamber with the high-pressure branch 24 and the increasing pressure space with the low pressure branch 26 connected is.

The adjustable hydraulic motor 8th assigned print network 6 is designed as a closed hydraulic circuit. To compensate for Lekageverluste and to avoid excessive heating of the pressure medium, this can be done via a Speisespüleinheit 35 be replaced with pressure medium from a tank. The generator 10 is from the hydraulic motor 8th over a wave 34 driven, so that the hydraulic energy is converted into electrical energy and into the power grid 36 is fed. The adjustment of the swivel angle of the hydraulic motor 8th and its Drehzahlregelnug via a secondary control, wherein in 1 the essential components of this electronic control circuit 12 are shown. The speed n _{act of} the generator 10 or the hydraulic motor 8th is with the of a control unit 38 predetermined target speed n _com compared and in a speed controller 40 introduced, which may have, for example, a PID transmission behavior. The output signal of the speed controller corresponding to the setpoint of the swivel angle 40 is via a Schwenkwinkelaufnehmer 42 detected and compared with the swivel angle actual value and the resulting voltage difference in the swivel angle controller 44 brought in. The output signal of the swivel angle controller 44 then supplies the control voltage for a control amplifier of a servo valve 46 , over which then the torque motor of the servo valve 46 is controlled to the swivel angle via a control cylinder 48 to adjust. This is also designed as a synchronous cylinder, wherein the annular spaces on the servo valve 46 with a pressure medium source 49 or the tank T is connectable.

With regard to further details and advantages of such secondary regulations, reference is made to the existing specialist literature, for example the hydraulic trainer volume 6, "Hydrostatic drives with secondary control", Vereinigte Fachverlage Mainz, 2nd edition 1995 directed.

2 shows the pressure net 6 associated food purifier 35 in detail. Because the basic construction of such food purifying units, for example, from DE 10 2005 051 324 A1 is known, only the essential components of the unit are described below.

According to 1 is the food purifier 35 with a high pressure line 50 to the high pressure branch 24 and with a low pressure line 52 to the low pressure branch 26 connected. The food purifier 35 has a feed pump 54 , which is designed as a fixed displacement pump and whose output with a feed line 56 connected is. The pressure in the feed line 56 can via a pump pressure relief valve 58 be limited to a maximum pressure. In the feed line 56 is a pressure reducing valve 58 arranged to set a feed pressure. Downstream of the pressure reducing valve 58 opens the feed line 56 in a high-pressure branch line 60 and a low pressure branch line 62 one, in each case one towards the feed pump 54 locking check valve 64 respectively. 66 is arranged. The high pressure branch line 60 opens into the high pressure line 50 and the low pressure branch line 62 in the low pressure line 52 one. The high pressure line 50 and the low pressure line 52 are over two pressure limiting lines 68 . 70 interconnected, wherein in the pressure limiting line 68 an opening in the direction of the low pressure side HD pressure relief valve 72 and in the pressure limiting line 70 an ND pressure relief valve opening toward the high pressure side 74 is provided.

Parallel to the two pressure limiting lines 68 . 70 runs a nozzle line 76 in which two spaced apart nozzles 78 . 80 are arranged, between which a tank channel 81 branches off to the tank T. About these nozzles 78 . 80 can each have a small amount of pressure medium from the high-pressure branch 24 and the low pressure branch 26 flow out to the tank T out, so that heating of the pressure medium in the pressure network 6 is prevented.

The food purifier 35 also has a purge valve 82 , with its two input connections to the high pressure line 50 and the low pressure line 52 connected. The flush valve 82 is designed as a 3/3-way valve, the output port via a purge line 84 connected to the tank T. In the flushing line 84 are a pressure relief valve 86 and a nozzle 88 arranged, the latter between the pressure relief valve 86 and the purge valve 82 is provided. Switching the purge valve 82 occurs as a function of the pressure difference between the high pressure line 50 and the low pressure line 52 , The applied pressures are at the control sides of the purge valve 82 guided. The pressure in the high pressure line acts 50 in the direction of the (b) marked switching position and the pressure in the low pressure line 52 in the direction of the (a) marked switching position. As usual, the pressure in the high pressure line 50 higher than in the low pressure line 52 is, the purge valve is 82 adjusted to its switching position (b), in which case the purge line 84 with the low pressure line 52 connected, so that the pressure medium in this area over the nozzle 88 and the pressure relief valve 86 can flow to the tank T. When the pressure in the high-pressure line drops 50 below the pressure in the low pressure line 52 becomes the purge valve 82 shifted in its position marked with (b), in which then the pressure medium in the high pressure line 50 and in the high-pressure branch 24 can flow to the tank T. In this case, then, according to the pressure medium volume flows flowing to the tank via the feed pump 54 Pressure medium in the high-pressure branch 24 and the low pressure branch 26 fed. The pressures at the outlet of the feed pump 54 , downstream of the pressure reducing valve 58 , in the wires 50 . 52 and the pressure difference across the nozzle 88 in each case via pressure transducers marked with the circle symbols 90 captured and to the control unit 38 reported by the system.

With the above solution, the tilt angle of the hydraulic motor 8th always adjusted so that the generator 10 revolves at the same speed (for example 1500 revolutions / min.). In the case where the speed of the generator 10 begins to decrease, the swivel angle is briefly increased to increase the displacement. Upon reaching the desired speed of the swivel angle is then pivoted back.

In the case where that of the pump 14 provided pressure drops, this can be compensated by the swing angle by the hydraulic motor 8th is set to a larger swallow volume.

Disclosed is a hydraulic / electrical converter with one of a natural force driven pump, over which a hydraulic accumulator charged and a hydraulic motor is driven. The latter drives a generator to convert the hydraulic energy into electrical energy at. According to the invention, the rotational speed of the hydraulic motor via set a secondary control.

2

pump

4

hydraulic rectifier

6

pressure network

8th

hydraulic motor

10

generator

12

loop

14

Rod cylinders

16

piston

18

pressure line

20

pressure line

22

way valve

24

High pressure branch

26

Low pressure branch

28

High-pressure accumulator

30

Low-pressure accumulator

32

transducer

34

wave

35

Speisespüleinheit

36

power grid

38

control unit

40

Speed governor

42

Swivel angle transducer

44

Swivel angle controller

46

servo valve

48

actuating cylinder

49

pressure source

50

High-pressure line

52

Low-pressure line

54

feed pump

56

feeder

57

Pump pressure relief valve

58

Pressure reducing valve

60

High pressure branch line

62

Low pressure branch line

64

check valve

66

check valve

68

Pressure relief line

70

Pressure relief line

72

HD-relief valve

74

ND-pressure relief valve

76

nozzle line

78

jet

80

jet

81

tank channel

82

flush valve

84

flushing line

86

Pressure relief valve

88

jet

90

Pressure transducer

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - US 6300689 B1 [0002, 0022]
• - DE 102005051324 A1 [0027]

Cited non-patent literature

• - "Hydrostatic drives with secondary control", Vereinigte Fachverlage Mainz, 2nd edition 1995 [0026]

Claims (10)

Hydraulic / electrical converter with a preferably powered by a natural force pump ( 2 ), via which a hydraulic accumulator ( 28 ) and a hydraulic motor ( 8th ), which in turn drives a generator for converting the hydraulic energy into electrical energy, characterized in that the hydraulic motor ( 8th ) to a print network ( 6 ) and is speed controlled. Converter according to claim 1, wherein the speed control is electro-hydraulic. Transducer according to claim 1 or 2, wherein between pump ( 2 ) and hydraulic motor ( 8th ) a hydraulic rectifier ( 4 ) is arranged. Transducer according to claim 3, wherein the rectifier ( 4 ) a directional control valve ( 22 ), which depends on the direction of movement of the pump ( 2 ) is switchable. Transducer according to claim 4, wherein the directional control valve ( 22 ) has a blocking position in which the pressure medium connection between the pump ( 2 ) and hydraulic motor ( 8th ) is interrupted. Converter according to one of the preceding claims, wherein the speed control a position control of an actuator of the hydraulic motor ( 8th ) is subordinate. Transducer according to one of the preceding claims, wherein in the printing network ( 6 ) a low-pressure accumulator ( 30 ) is arranged. Transducer according to one of the preceding claims, wherein the printing network ( 6 ) is a closed circuit. Transducer according to one of the preceding claims, wherein the printing network ( 6 ) a food purifier ( 35 ) assigned. Transducer according to one of the preceding claims, wherein the pump ( 2 ) a hydraulic cylinder actuated by the swell ( 14 ).