GB2491723A - Hydraulic drive with control surfaces of directional control valve pressurised by two separate working lines - Google Patents
Hydraulic drive with control surfaces of directional control valve pressurised by two separate working lines Download PDFInfo
- Publication number
- GB2491723A GB2491723A GB201210292A GB201210292A GB2491723A GB 2491723 A GB2491723 A GB 2491723A GB 201210292 A GB201210292 A GB 201210292A GB 201210292 A GB201210292 A GB 201210292A GB 2491723 A GB2491723 A GB 2491723A
- Authority
- GB
- United Kingdom
- Prior art keywords
- pressure
- valve
- working
- low
- working line
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B11/00—Servomotor systems without provision for follow-up action; Circuits therefor
- F15B11/08—Servomotor systems without provision for follow-up action; Circuits therefor with only one servomotor
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B2211/00—Circuits for servomotor systems
- F15B2211/20—Fluid pressure source, e.g. accumulator or variable axial piston pump
- F15B2211/205—Systems with pumps
- F15B2211/2053—Type of pump
- F15B2211/20546—Type of pump variable capacity
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B2211/00—Circuits for servomotor systems
- F15B2211/20—Fluid pressure source, e.g. accumulator or variable axial piston pump
- F15B2211/205—Systems with pumps
- F15B2211/2053—Type of pump
- F15B2211/20569—Type of pump capable of working as pump and motor
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B2211/00—Circuits for servomotor systems
- F15B2211/30—Directional control
- F15B2211/32—Directional control characterised by the type of actuation
- F15B2211/329—Directional control characterised by the type of actuation actuated by fluid pressure
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B2211/00—Circuits for servomotor systems
- F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
- F15B2211/705—Output members, e.g. hydraulic motors or cylinders or control therefor characterised by the type of output members or actuators
- F15B2211/7051—Linear output members
- F15B2211/7053—Double-acting output members
Landscapes
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Fluid Mechanics (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Fluid-Pressure Circuits (AREA)
Abstract
Disclosed is a hydraulic drive for supplying a double-acting consumer 1, in particular a cylinder or a motor, via two working lines 6,8 which are each assigned a movement direction of the consumer 1, high pressure prevailing in the one working line and low pressure prevailing in the other working line, in accordance with the direction of the applied force. The working lines 6,8 are connected to a directional control valve 10, the valve body of which has a first control surface 35 and a second control surface 37, which act in opposite directions to one another. The first control surface 35 can be pressurised with the pressure of the first working line 6, while the second control surface 37 can be pressurised with the pressure of the second working line 8. As a result, the higher-load working line is always connected via the directional control valve 10 to a high-pressure port 14 of a hydraulic machine 16, in particular hydraulic pump, while the lower-load working line is connected via the directional control valve 10 to a low-pressure port 20 of the hydraulic machine 16.
Description
Hydraulic drive
Description
The invention relates to a hydraulic drive according to the preamble of Claim 1.
The publication 05 6,789,387 82 discloses such a drive for a double-acting cylinder, in which the pressure in the two working spaces of the cylinder or in the assigned working lines is monitored. From this, the operating or loading situation of the cylinder is detected by an electronic control unit. Accordingly, the control unit switches a directional control valve, via which one of the two working lines is connected to a high-pressure port of a pump, while the other working line is relieved to tank.
The disadvantages of such hydraulic drives with largely electronified determination of the loading situation and with electronic switching of the directional control valve are the fault liability of the additional electronics in an otherwise hydraulic drive and the dependence on additional external activation energy.
Against this background, the object of the invention is to provide a hydraulic drive in which these disadvantages are eliminated.
This object is achieved by a hydraulic drive having the features of Claim 1.
The hydraulic drive according to the invention serves for supplying a double-acting hydraulic consumer, in particular a hydraulic cylinder or a hydraulic motor, via two working lines which are each assigned a movement direction of the consumer, high pressure prevailing in the one working line and low pressure prevailing in the other working line, in accordance with the direction of the applied force. The working lines are connected to a directional control valve, the valve body of which has a first control surface and a second control surface, which act in opposite directions to one another. The first control surface can be pressurised with the pressure of the first working line, while the second control surface can be pressurised with the pressure of the second working line. As a result, the higher-load working line is always connected via the directional control valve to a high-pressure port of a hydraulic machine -in particular hydraulic pump -, while the lower-load working line working line is connected via the directional control valve to a low-pressure port of the hydraulic machine. Thus, a hydraulic determination of the loading situation and a direct hydraulic control of the directional control valve are possible, in which no e.s sa* * electronic devices are necessary and which functions independently of electrical energy.
In a preferred development of the invention, the first control surface is always pressurised. with the pressure of the first working line, while the second control surface is always pressurised with the pressure of the second working line. Thus, apart from the switching of the directional control valve, no further switching operations are necessary.
Further advantageous configurations of the invention are described in the dependent claims.
In a particularly preferred development of the invention, a delivery volume of the hydraulic machine is adjustable in dependence on an operating element or an operating unit.
Thus, an operating wish regarding the movement of the consumer can be picked up and the delivery volume controlled, for example via a swivelling angle or via a digitally controlled opening time of individual working spaces of the hydraulic machine.
If the operating wish results in a lowering of a load via the consumer configured as a cylinder or a braking of a rotary movement of the consumer configured as a motor, the hydraulic machine can act as a motor and regenerate the corresponding energy.
If the operating unit and a position sensor assigned to the valve body are connected to an electronic control unit, the latter can determine from the position of the valve piston :.:.:; which side or which working line of the consumer is * connected to the hydraulic machine. It is thus possible to provide the delivery direction (i.e. pump or motor function) the volume flow through the hydraulic machine, depending on the movement direction -preset via the operating unit.
In one possible application, the consumer is a differential cylinder, the piston of which has two unequal pressure surfaces acting against one another. It is then preferred if the two control surfaces of the valve piston have the same area ratio as the two pressure surfaces of the piston.
The valve piston can thus compare the forces acting on the differential cylinder.
If the low-pressure port of the hydraulic machine and thus also the lower-load working line connected via the directional control valve are connectable to a tank, a semi-closed circuit is created.
In this case, it is preferred if a nonreturn valve is arranged between the low-pressure port and the tank, which valve opens from the tank towards the low-pressure port.
This valve serves for feeding pressure medium, in * particular if the consumer is a differential cylinder, to the piston head space of which pressure medium is delivered. In this case, the pressure medium displaced from the annular space is not sufficient to provide the pressure * medium delivered to the piston head space. * .
Furthermore, it is preferred if a spring-biased nonreturn valve is arranged between the low-pressure port and the a. a. tank, which valve opens from thelow-pressure port towards * the tank. This valve serves for discharging excess pressure *as.a medium, in particular if the consumer isa differential cylinder, to the annular space of which pressure medium is d!livered. In this case, the pressure medium displaced from the piston head space cannot be fully taken up by the annular space.
In a particularly preferred development of the invention, the hydraulic machine is digitally variable. In this case, each cylinder/piston unit of the hydraulic machine has an actively controllable low-pressure valve and an actively controllable high-pressure valve. If the hydraulic machine is not to be employed as a motor for energy recovery, the high-pressure valves may also be passive nonreturn valves.
The hydraulic machine -in particular in the development as a digitally variable machine -is preferably a radial piston machine. This is also referred to as a digital variable radial piston machine (DVR) If the directional control valve is a 4/3-way valve with a central blocking position, low-leakage holding of the consumer -in particular cylinder -is possible. /
If the pressure of the two working lines is equal, a state of the directional control valve and thus of the drive according to the invention can arise in which the operating position of the valve body is rnetastable or undefined. In order to avoid this, the two following developments are * 0**ss preferred.
In addition to the two control surfaces, the valve body can be assigned two electromagnetic actuators, the effective directions of which are opposite to one another and which * can be activated by control unit.
The two control surfaces can be connectable via respective control lines to the assigned working lines, in each control line there being arranged a shuttle valve. Via the shuttle valves, the control surfaces are connectable via a common pilot control valve to the high-pressure port of the hydraulicmachine, which pilot control valve is switched by the control unit for this purpose.
Both developments serve to avoid a metastable or undefined state of the valve body and "in case of doubt" to moVe the valve body via the control unit to a defined operating position.
In both developments, it is preferred if the force application is significantly below that of the control surfaces connected to the working lines, so that the latter predominates as soon as a low load acts on the consumer.
Different exemplary embodiments of the invention are described in detail below with reference to the figures, in which: Figure 1 shows a circuit diagram of a first exemplary embodiment of a drive according to the invention.in a first operating state, * Figure 2 shows a circuit diagram of the first exemplary embodiment of the drive according to the invention in a second operating state, Figure 3 shows a circuit diagram of the first exemplary embodiment of the drive according to the invention in a * third operating state, Figure 4 shows a circuit diagram of the first exemplary embodiment of the drive according to the invention in a fourth operating state, Figure 5 shows a circuit diagram of a second exemplary embodiment of the drive according to the invention, and Figure 6 shows a circuit diagram of a third exemplary embodiment of the drive according to the invention.
Figures 1 to 4 each show a circuit diagram of a first exemplary embodiment of a drive according to the invention for a differential cylinder 1. The latter has an annular space 2 and a head space 4. The head space 4 is connected via a first working line 6, and the annular space 2 is connected via a second working line 8, to a 4/3-way valve 10. Via the directional control valve 10, the two working lines 6, 8 can be connected via a high-pressure line 12 to a high-pressure port 14 of a digitally variable hydraulic machine 16 or to a low-pressure line 18. The low-pressure line 18 branches to a tank T and to a low-pressure port 20 of the hydraulic machine 16. The hydraulic machine 16 is one with a series of piston/cylinder units of radial or axial piston design, each piston/cylinder unit being assigned an actively, e.g. electromagnetically, controllable, high-pressure valve and an actively controllable low-pressure valve. Via the high-pressure valve, the working space of a piston/cylinder unit is connectable to a pressure port, and via the low-pressure S....
* valve it is connectable to a low-pressure or suction port, of the hydraulic machine. Thus, each cylinder/piston unit ** can be operated independently of the other units in a pump mode, in a motor mode or in an' idle mode. In the pump mode, on a piston movement in the sense of. reducing the working' * space, the low-pressure valve is closed and the high-pressure valve is open and, on a piston, movement in the sense of increasing the working space, the low-pressure valve is open and the high-pressure valve is closed. In the motor mode, on a piston movement in the sense of reducing the working space, the low-pressure valve is open and the high-pressure valve is closed and, on a piston movement in the sense of increasing the working space, the low-pressure valve is closed and the high-pressure valve is open. In the idle mode, the corresponding unit isdeactivated by permanent opening of its low-pressure valve and by permanent closing of its high-pressure valve. In this way, the swept volume (pump operation) and the absorbing volume (motor operation) of the hydraulic machine 16 can be varied in steps, i.e. digitally.
If the hydraulic machine 16 acts as a pump, it is driven via a motor 26. The hydraulic machine 16 has a plurality of cylinder/piston units (not shown specifically), each unit being assigned an actively controllable high-pressure valve and an actively controllable low-pressure valve.
In the connection of the low-pressure line 18 to the tank T, a nonreturn valve 22 which opens from the tank T towards the low-pressure line 18 and a spring-biased nonreturn valve 24 which opens from the low-pressure line 18 towards the tank T are arranged in parallel with one another. * *n* * *
The drive furthermore has an electronic control unit 26.
**:* The lattr controls the various high-pressure and low-pressure valves of the hydraulic machine 16 via a signal line 30. ** S. * S * * *
The control unit 28 is connected to an operating unit 32, via which an operator can preset the desired movement direction and speed of a piston of the differential cylinder 1.
To the first working line 6 is connected a first control line 34, via which a valve body of the directional control valve 10. is pressurised (in Figures 1 to 4) towards the right via a control pressure and a first control surface 35 in the direction of an operating position in which the * high-pressure line 12 is connected to the first working line 6 and the low-pressure line 18 is connected to the second working line 8. To the second working line 8 is connected a second control line 36, via which the valve body of the directional control valve 10 is pressurised (in Figures 1 to 4) towards the left via a control pressure and a second control surface 37 in the direction of an operating position in which the high-pressure line 12 is connected to the second working line 8 and the tow-pressure line 18 is connected to the first working line 6. With this pressurisation by control pressure, the higher-load working space 2, 4 of the differential cylinder 1 is always connected to the high-pressure tine 12 and thus to the high-pressure port 14 of the hydraulic machine 16.
Furthermore, the lower-load working space 2, 4 is always connected via the low-pressure line 18 in particular to the low-pressure port 20 of the hydraulic machine 16 and furthermore to the tank T. The directional control valve 10 * **esS * is assigned a position sensor 38, via which the position of the valve body and thus the loading situation of the differential cylinder 1 are indicated to the control unit 28. Together with the operator's wish indicated via the operating unit 32, the control unit 28 can detect and *Sses* * * control the following four operating states of thedrive according to the invention: -lift against a load force according to Figure 1; -lift with assistance of a load force according to Figure 2; -lower with assistance of a load forèe according to Figure 3; and -lower against a load force according to Figure 4.
In Figure 1,a load force F acts downwards according to the arrow F, so that high pressure prevails in the head space 4 and low pressure prevails in the annular space 2. As a result, according to the invention, the directional control valve 10 is switched such that the head space 4 is connected to the high-pressure port 14 of the hydraulic machine 16. The operator's wish to "lift" is symbolised by a lever of the operating unit 32 in a right-hand position according to Figure 1. Accordingly, the various high-pressure and low-pressure valves of the digital hydraulic machine 16 are opened and closed such that the hydraulic machine 16 acts as a pump and lifts the piston of the differential cylinder 1 according to the arrow X against the load force F. Figure 2 shows the operator's wish unchanged as "lift", * with a pulling, upwardly directed load force F according to * * * * ** ( * Figure 2 acting. As a result, high pressure prevails in the * S. S..
* S annular space 2. Accordingly, the valve body of the directional control valve 10 is set into the right-hand operating position illustrated in Figure 2, whereby the annular space 2 is connected to the hydraulic machine 26.
* The pressure medium of the annular space 2 is displaced or S.....
* * delivered to the hydraulic machine 16, which works as a motor. The corresponding energy can be utilised at the same time for other purposes or stored.
Figure 3 shows the operator's wish as "lower". In this case, the load force F corresponds to that of Figure 1 and acts such that high pressure prevails in the head space 4.
Accordingly, the directional control valve 10 connects the head space 4 to the hydraulic machine 16, which acts as a motor in the operating state shown in Figure 3..
Figure 4 shows the operator's wish again as "lower", with a load force F being directed opposite to the operator's wish. Accordingly, high pressure builds up in the annular space 2, and the annular space 2 is connected to the hydraulic machine 16 acting as a pump.
The first exemplary embodiment of the drive according to the invention according to Figures I to 4 has a connection of the low-pressure line 18 or of the low-pressure port 20 to the tank T, in particular to compensate for pressure- medium deficiency or pressure-medium excess in the semi-closed circuit. In this case, the nonreturn valve 22 serves as a feed valve in both operating states according to Figures 1 and 2, while the spring-biased nonreturn valve 24 serves to discharge excess pressure medium in the operating states according to Figures 3 and 4.
S.....
* Figure 5 shows a second exemplary embodiment of the drive according to the invention. In this case, the essential difference from the first exemplary embodiment according to Figures 1 to 4 is that, in addition to the two control * lines 34, 36, two electromagnetic actuators 140a, 140b are *Se*S* * * provided in order to avoid an undefined or metastable state of a valve body of a 4/3-way valve 110. These actuators are controllable by an electronic control unit 128, so that if there is equal pressure in the two working spaces 2, 4 of the differential cylinder 1 the valve body can be switched to a defined operating position. In this case, the forces of the two actuators l4Oa, NOb are relatively low, so that as soon as an uneven pressure starts to build up in the two working spaces 2, 4 the connection, according to the invention, of the higher-load working space 2, 4 to the high-pressure port 14 of the hydraulic machine 16 via, the control lines 34, 36 is established.
Figure 6 shows a third exemplary embodiment of the drive according to the invention. In this case, the essential difference from the first exemplary embodiment according to Figures 1 to 4 is that in the two control lines 34, 36 respective shuttle valves 240a, 24Db are provided in order to avoid an undefined or metastable state of a valve body of a 4/3-way valve 210. These shuttle valves 240a, 24Db are connected to a pilot control valve 242, via which one of the two shuttle valves 240a, 24Db can be pressurised with control pressure, irrespective of the loading situation of the differential cylinder 1. In this case, the corresponding shuttle valve 240a, 24Db opens a connection from the pilot control valve 242 to the assigned control surface 35, 37 on the valve body of the directional control valve 210.
* .tti* * S The pilot control valve 242, which is configured as a 3/3- *. way valve, is controlled by a control unit 228. Thus, if there is equal pressure -in particular at low pressures in the two operating spaces 2, 4 of the differential *sSs* * * cylinder 1, the valve body of the directional control valve 210 can be switched to a defined operating position. In this case, the control forces switched via the pilot control valve 242 are relatively low, so that as s'oon as an uneven pressure starts to build up in the two workingS spaces 2, 4 the shuttle valves 240a, 24Db open the connection of the higher-load working space 2, 4 to the high-pressure port 14 of the hydraulic machine 16 via the control lines 34, 36 again.
Disclosed is a hydraulic drive for supplying a double-acting consumer, in particular a hydraulic cylinder or a hydraulic motor, via two working lines which are each assigned a movement direction of the consumer, high pressure prevailing in the one working line and low pressure prevailing in the other working line, in accordance with the direction of the applied force. The working lines are connected to a directional control valve, the valve body of which has a first control surface and a second control surface, which act in opposite directions to one another. The first control surface can be pressurised with the pressure of the first working line, while the second control surface can be pressurised with the pressure of the second working line. As a result, the higher-load working line is always connected via the directional control valve to a high-pressure port of a hydraulic machine -in particular hydraulic pump -, while the lower-load working line is connected via the directional control S.....
* . valve to a low-pressure port of the hydraulic machine. * St * S S * S. a S..
S S. Se * S * * S *SS5
S S
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE201110103872 DE102011103872A1 (en) | 2011-06-10 | 2011-06-10 | Hydraulic drive |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB201210292D0 GB201210292D0 (en) | 2012-07-25 |
| GB2491723A true GB2491723A (en) | 2012-12-12 |
Family
ID=46605747
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB201210292A Withdrawn GB2491723A (en) | 2011-06-10 | 2012-06-08 | Hydraulic drive with control surfaces of directional control valve pressurised by two separate working lines |
Country Status (2)
| Country | Link |
|---|---|
| DE (1) | DE102011103872A1 (en) |
| GB (1) | GB2491723A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104088827A (en) * | 2014-07-17 | 2014-10-08 | 常州爱普超高压液压系统有限公司 | Hydraulic overturning device for pontoon bridge gangplank |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1585796A (en) * | 1976-07-07 | 1981-03-11 | Bosch Gmbh Robert | Hydraulic control system for at least two loads |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6789387B2 (en) | 2002-10-01 | 2004-09-14 | Caterpillar Inc | System for recovering energy in hydraulic circuit |
-
2011
- 2011-06-10 DE DE201110103872 patent/DE102011103872A1/en not_active Withdrawn
-
2012
- 2012-06-08 GB GB201210292A patent/GB2491723A/en not_active Withdrawn
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1585796A (en) * | 1976-07-07 | 1981-03-11 | Bosch Gmbh Robert | Hydraulic control system for at least two loads |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104088827A (en) * | 2014-07-17 | 2014-10-08 | 常州爱普超高压液压系统有限公司 | Hydraulic overturning device for pontoon bridge gangplank |
| CN104088827B (en) * | 2014-07-17 | 2016-04-06 | 靖江市维益知识产权服务有限公司 | Bridge of boats springboard hydraulic pressure turn-over device |
Also Published As
| Publication number | Publication date |
|---|---|
| GB201210292D0 (en) | 2012-07-25 |
| DE102011103872A1 (en) | 2012-12-13 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |