EP0417087A1 - Electrohydraulic guide system. - Google Patents
Electrohydraulic guide system.Info
- Publication number
- EP0417087A1 EP0417087A1 EP88904705A EP88904705A EP0417087A1 EP 0417087 A1 EP0417087 A1 EP 0417087A1 EP 88904705 A EP88904705 A EP 88904705A EP 88904705 A EP88904705 A EP 88904705A EP 0417087 A1 EP0417087 A1 EP 0417087A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- pressure
- objects
- valve means
- fluid source
- volume flow
- 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.)
- Granted
Links
- 239000012530 fluid Substances 0.000 claims abstract description 50
- 238000000034 method Methods 0.000 claims description 18
- 230000001133 acceleration Effects 0.000 claims description 8
- 230000000694 effects Effects 0.000 claims description 3
- 238000005259 measurement Methods 0.000 claims description 3
- 230000006870 function Effects 0.000 abstract description 7
- 230000007423 decrease Effects 0.000 description 4
- 238000010276 construction Methods 0.000 description 2
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000015654 memory Effects 0.000 description 1
- 238000005086 pumping Methods 0.000 description 1
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
- F15B21/00—Common features of fluid actuator systems; Fluid-pressure actuator systems or details thereof, not covered by any other group of this subclass
- F15B21/08—Servomotor systems incorporating electrically operated control means
Definitions
- the present invention relates to a method and an apparatus of the kind stated in the preamble part of the claims 1 and 10/ respectively.
- Modern guide systems and valves governing several objects from a common pressure fluid source are more and more of ⁇ ten constructed such that they receive a so called load- sensing function. Upon load-sensing it is scanned among the objects being activated and which receive volume flow from supply or pressure conduit out to the object requi- ring the highest pressure. In a fully hydraulic solution this is obtained by using several different back valves. The highest sensed pressure is returned to the pressure fluid source and governsthe source such that it governs out the return pressure plus in addition as much as is required for the valve to be able to govern the volume flow with a pressure drop of usually about 25 bar. Thus, the object requiring the highest pressure is like the other objects loaded by an energy loss unnecessary per se.
- each object must then have at least one transmitter for each force direction, i.e. two transmitters for double- acting cylinders and motors, and also at least one pressure transmitter positioned on the supply conduit from the pres- sure fluid source to the valves of the objects. Since elect ⁇ ric pressure transmitters are considered to involve high costs and lower reliability than fully hydraulic devices based on back valves the fully hydraulic alternative has up to now been predominant.
- the load-sensing systems have not been developed as rapidly and received the large marked share as many have expected. The explana ⁇ tion to this is probably that the advantages have not been considered to balance the increased cost.
- Electrohydraulic guide systems have rapidly been developed and take continuously larger and larger market shares. High demands on automatization, increased supervision and secu ⁇ rity press on the development towards electrohydraulic systems having positiontrans ⁇ tters and ability for position governing. Microprocessors and better transmitters for pres ⁇ sure and position make today advanced guide technique pos ⁇ sible as to both function and cost.
- a relatively rapid and intensive development of the electrohydraulic has, however, mainly been directed towards improvements of the conventio ⁇ nal hydraulic components and guide principles with electro ⁇ hydraulic solutions rather than to create new guide prin ⁇ ciples and components adapted to the completely new con ⁇ ditions that the access to microprocessors and transmitters provides.
- the present invention which accordingly relates to a method and an apparatus for electrohydraulic governing of several objects from a pressure fluid source, makes possible to unite the functions such as load-sensing with a minimum pressure increase, the ability of position gover ⁇ ning and signal treatment in microprocessors with an eco ⁇ nomic construction requiring a minimum of transmitters and highly simplified hydraulic components and elements.
- the invention have not in view to improve old governing prin ⁇ ciples or components but instead provides a new concept for electrohydraulic with the possibility of governing both position, speed and acceleration. Since the inven ⁇ tion furthermore provides a flexible system construction, the system can with the aid of electric pressure transmit ⁇ ters in existing cases also govern pressure, i.e. force or moment. - " ' The characteristics of the invention appear from the claims.
- the invention includes position transmitters and proceeds from that these transmitters are a self-evident condition for an effective, flexible and reliable gover ⁇ ning system, these transmitters are not possible to elimi ⁇ nate out of the method or the apparatus but are a condi ⁇ tion for each satisfactory governing system.
- Other transmit ⁇ ters have not the same self-evident position in the governing system.
- the present invention provides a method and an apparatus mainly only requiring position transmitters on the objects in order to be able to co-drive the pressure fluid source and the objects without any appreciable up-building of pressure above the pressure that the object having the highest pressure requires.
- This simple and cost-saving guide system requires in order to operate a combination of three measures. Firstly, the position on the objects must be measured and the measure values returned to the electro ⁇ nic system, which then also can calculate the speed and acceleration of the objects. Secondly, the valves gover- ning each object shall never allow input signal to govern out more than what is possible to realize in view of limi ⁇ tations of the capacity of the pressure fluid source, i e the volume flow which in every moment can be supplied to the objects via the common supply conduit.
- the pressure fluid source shall for avoiding up-building of pres ⁇ sure in every moment be governed such that it delivers to the supply conduit a small quantity less volume flow than the valves of the objects try to govern out from the supp ⁇ ly conduit to the objects.
- the valve governing the object having the highest pressure can in such a case not receive the volume flow it strives to govern out. It will then open to a comparatively large extent resulting in a low pressure drop over the valve and low system pressure in the supply conduit.
- the governing of the pressure fluid source takes place by means of guide signals of the type increase or decrease.
- the information to these guide signals arrives from the position transmitter of the objects, i.e. from the information about the posi- • tion, speed and acceleration of the objects.
- the electro ⁇ nic system registers and adds thespeeds of each object and registers and adds a test point which is applicable to each object.
- the pressure fluid source is governed for increase or decrease of its delivered volume flow so that the deli ⁇ vered volume flow is a small quantity lower than the volume flow which should give all objects the speed that each ob- ject valve strives to govern out.
- a method and and apparatus is provided which lacks parti ⁇ cular means for pressure-sensing and which instead causes that the object requiring, the highest pressure directly via a comparatively low pressure drop over the valve of the object directly governs the pressure in the SUDPIV con ⁇ duit.
- the governing of the object having the highest pres ⁇ sure requirement will in this manner first-hand to be gover ⁇ ned by the governing of the pressure fluid source.
- the valve of the object tries all the time to govern the speed of the object towards the value that the input sig ⁇ nal indicates, and when the object changes from requiring the highest pressure to some lower pressure, the valve of the object takes over the governing from the pressure fluid source.
- the function is realized by the electronic system and by only comparison of real and desired values for the speeds of the different objects.
- the cost for the load-sensing co-driving of object and pressure fluid source is very low.
- valves guiding the volume flow to and from the objects can be constructed in many ways.
- the valves are constructed such that the inlet side can be closed when the volume flow is governed from the object to the return con- duit to tank.
- the governing of the volume flow to and from the object should preferably be formed such that automatically the inlet volume flow will give a higher, for instance 30%, object speed than the return volume flow.
- unneeded pressure up-building in the valves of the objects is avoided. The- result of this is that when a load for instance is lifted, i.e.
- the speed of the valve is governed on" the inlet side, whereby the pressure drop on the outlet side to the return conduit is low, or when for instance a load is lowered, i.e. when the object is energy delivering and operates as a pump, the speed of the valve on the outlet side is governed, wherein with advantage as large part as possible of the inlet volume flow can be delivered from the return conduit via back valves, so called anticavitation valves.
- pressure and force can of course be governed.
- An electric transmitter is then arranged on the object on the side where the pressure shall be governed.
- the valve of the object is now governed such that the inlet side opens and governs the pressure when this shall increase and the outlet side go ⁇ verns the pressure when this shall decrease.
- the position transmitters of the objects measure the received volume flow to the objects and owing to the fact that via the inlet signals to the object valves it.is with the aid of the electronic guide system possible to determinewhich volume flow that flows from the supply conduit to the objects, the total volume flow flowing from the supply conduit to the objectscan with sufficient accu- racy easily be calculated. If a volume flow meter is in ⁇ serted after the pressure fluid source in the supply con ⁇ duit a fast indication can be obtained if the supply con ⁇ duit should brake or a larger leakage should arise. It is accordingly with the aid of the electronic system possible to obtain an out-pumping protection which automatically and very rapidly closes the pressure fluid source.
- Fig. 1 schematically shows an apparatus according to the invention with components included in the apparatus
- Fig. 2 schematically shows another embodiment of a part of the apparatus according to Fig. 1
- Fig. 3 schematically shows another embodiment of another part of the apparatus according to Fig. 1.
- the embodiment shown in Fig. 1 includes an outer impulse generating guide means 1 , which for instance is governed by an operator and which delivers desired values to an electronic guide system 2.
- the guide system 2 governs a number of objects for driving a machine, for instance a crane. Two such objects 3 and 4 are shown in Fig. 1.
- the guide system 2 also governs a pressure fluid source 5 via an electric set device 6.
- the object 3 is of linear type, a hydraulic cylinder, and is provided with a position transmitter 7, for instance a potentiometer, digital transmitter, or another conventional transmitter, and the object 3 is governed by a valve 8 con ⁇ nected to a pressure or supply conduit 9 from the pressure fluid source 5 and to a return conduit 10 connected to a tank 11.
- the object 4 is exemplified shown to be of rota ⁇ ting type and is provided with a position transmitter 12 and is governed by a valve 13 connected to the supply con ⁇ duit 9 and the return conduit 10.
- the objects 3, 4 and eventually other objects not shown are connected in parallel to the supply conduit 9 and the return conduit 10.
- the guide system 2 receives signals about desired movements from the outer guide means 1 and when required reduces the signals for instance proportionally down to such levels that the pressure fluid source can govern out the movements even possibly with lower speed via output signals to the ob ⁇ jects 3 and 4 governed by the valves 8 and 13.
- the guide system 2 via the set device 6 governs the pressure fluid source 5 for feeding to the supply conduit 9 a volume flow being a small quantity lower than the volume flow that the valves 8 and 13 try to govern from the supply conduit 9 to the objects 3 and 4.
- the governing of the pressure fluid source 5 takes place with the aid of the summing-up of the speeds that can be calculated with the aid of the information "from the position trans ⁇ mitters 7 and 12 and with the aid of the sum of the in- put signals delivered to the valves 8 and 13.
- the guide system is constructed such that it is essentially the position transmitters 7 and 12 and the calculations of speed and acceleration that the input signals to both the valves 8 and 13 of the objects 3 and 4 and the set device 6 of the pressure fluid source 5.
- the valves 8 and 13 can preferably be constructed such that they independent of the pressure drop over the valves 8 and 13 deliver a volume flow which is more or less proportio ⁇ nal to the input signals.
- the pressure fluid source 5 is preferably constructed as a variable reset pump but can also be a fixed non-reset pump provided with a shunt valve which via the set device 6 shunts undesired volume flow from the supply conduit 9 to the return conduit 10.
- the position transmitters 7 and 12 can be constructed in many ways, for instance be potentiometers or other all- electric devices. As position transmitters can also be used volume meters which measures the volume delivered out of or supplied into one side of the object and there ⁇ by calculate the position, the speed and the acceleration of the object. Measurement with volume meters is particu ⁇ larly useful in dangerous environments where electric transmitters can be unsuitable. Volume meters or trans ⁇ mitters can also, if they can be made with low cost and with good accuracy, be an alternative to all-electric position transmitters.
- Fig. 2 illustrates such an alternative having a volume meter 14 as position transmitter instead of a position transmitter 7 according to Fig. 1.
- the object 3 is const ⁇ ructed as a piston/cylinder-device and the volume meter 14 is arranged between the cylinder and a directional valve 15 provided with transmitter 16.
- Fig. 3 illustrates an embodiment in which a volume meter 17 is positioned in the supply conduit 9 after the pres ⁇ sure fluid source 5, and the volume meter 17 is connected to the guide system 2.
- a fast indication can be obtained if any leakage should arise, for instance hose brake in the supply conduit 9.
- the volume flow delivered from the pressure fluid source 5 is measured and is re ⁇ turned to the guide system 2 and is compared with the sum of all volume flows delivered from the supply conduit to the tank 11, and as measure value for each object 3, 4 is valid the volume flow calculatable from the position measurement by means of the position transmitters 7, 12, 14, or if another value exists, for instance 10% lower, the volume flow belonging to a flow from supply conduit to object proportional to the guide signal of the valve 8, 13, 15.
- the technique required for realizing the electronic guide system 2 is today known and commonly used for instance in numerically controlled machine tools and robots and in electronic guide systems in many other civil and military applications.
- An apparatus according to the invention can of course be completed with further functions, such as • memories etc, making possible for a machine guided by the apparatus to excercise and repeat as well as record move ⁇ ments automatically as well as for instance allow permitted and unper itted operation field and mode of movements.
- the permitted field can position y position be given a maximum speed making the speed softly decreasing towards the end positions and so that accelerations and dynamic forces are maximized.
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Physics & Mathematics (AREA)
- Fluid Mechanics (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Fluid-Pressure Circuits (AREA)
- Valve Device For Special Equipments (AREA)
Abstract
Description
Claims
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
SE8702064 | 1987-05-19 | ||
SE8702064A SE470109B (en) | 1987-05-19 | 1987-05-19 | Method and apparatus for electro-hydraulic control of movements of pressurized actuated objects connected to a device |
PCT/SE1988/000260 WO1988009442A1 (en) | 1987-05-19 | 1988-05-19 | Electrohydraulic guide system |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0417087A1 true EP0417087A1 (en) | 1991-03-20 |
EP0417087B1 EP0417087B1 (en) | 1995-11-15 |
Family
ID=20368564
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP88904705A Expired - Lifetime EP0417087B1 (en) | 1987-05-19 | 1988-05-19 | Electrohydraulic control method |
Country Status (6)
Country | Link |
---|---|
EP (1) | EP0417087B1 (en) |
JP (1) | JP2612202B2 (en) |
AT (1) | ATE130408T1 (en) |
DE (1) | DE3854694T2 (en) |
SE (1) | SE470109B (en) |
WO (1) | WO1988009442A1 (en) |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2647750B2 (en) * | 1991-02-08 | 1997-08-27 | 日立建機株式会社 | Actuator drive control device |
Family Cites Families (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4625622A (en) * | 1985-08-15 | 1986-12-02 | Vickers, Incorporated | Power transmission |
-
1987
- 1987-05-19 SE SE8702064A patent/SE470109B/en not_active IP Right Cessation
-
1988
- 1988-05-19 EP EP88904705A patent/EP0417087B1/en not_active Expired - Lifetime
- 1988-05-19 AT AT88904705T patent/ATE130408T1/en not_active IP Right Cessation
- 1988-05-19 JP JP63504526A patent/JP2612202B2/en not_active Expired - Lifetime
- 1988-05-19 WO PCT/SE1988/000260 patent/WO1988009442A1/en active IP Right Grant
- 1988-05-19 DE DE3854694T patent/DE3854694T2/en not_active Expired - Fee Related
Non-Patent Citations (1)
Title |
---|
See references of WO8809442A1 * |
Also Published As
Publication number | Publication date |
---|---|
SE8702064L (en) | 1988-11-20 |
JP2612202B2 (en) | 1997-05-21 |
JPH02503591A (en) | 1990-10-25 |
SE8702064D0 (en) | 1987-05-19 |
DE3854694T2 (en) | 1996-05-23 |
ATE130408T1 (en) | 1995-12-15 |
SE470109B (en) | 1993-11-08 |
DE3854694D1 (en) | 1995-12-21 |
WO1988009442A1 (en) | 1988-12-01 |
EP0417087B1 (en) | 1995-11-15 |
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