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
  • F15B3/00—Intensifiers or fluid-pressure converters, e.g. pressure exchangers; Conveying pressure from one fluid system to another, without contact between the fluids

Definitions

• the invention relates to a pressure booster for fluids, in particular for hydraulic fluids, with a piston-cylinder arrangement which has a low-pressure side with a low-pressure connection and a high-pressure side with a high-pressure connection and a supply connection, and an amplifier piston designed as a differential piston between the low-pressure and high-pressure sides, and with a control valve, which has a valve spool, which connects the low-pressure connection alternately to a pressure source and a pressure sink and is connected via a control line to the piston-cylinder arrangement, the pressure in the control line being on one side of the valve spool and on the other side of the Valve spool acts a constant pressure that the valve spool is designed as a differential piston and the valve spool is arranged to form an annular space in a valve housing into which a tank line and a pump line and in between e open into a cylinder line.
• Such a pressure booster is known from O + P " ⁇ lyhydraulik und Pneumatik” 37 (1993) No. 5, pages 418 and 420.
• Pressure boosters of this type serve to increase the pressure in a fluid beyond the pressure of a pressure source.
• the following explanation will be made using the example of hydraulic fluids. In principle, however, the principle also applies to other fluids.
• a similar pressure booster of the type mentioned is known from DE 40 26 005 A1.
• the known pressure booster is provided with a differential piston which acts as a booster piston.
• the booster piston has a low pressure piston which is arranged in a low pressure cylinder and a high pressure piston which is arranged in a high pressure cylinder. Both pistons are firmly connected to each other via a piston rod.
• the low pressure piston has a much larger cross section than the high pressure piston. The pressure ratio between the low pressure side and the high pressure side then takes place in the ratio of the piston cross sections.
• the terms "low pressure” and "high pressure” are used here and below only to distinguish the two sides. They do not represent absolute pressure values, only relative relationships.
• Hydraulic fluid is often taken off on the high pressure side, which must be adjusted with the appropriate pressure.
• the high pressure cylinder ie the pressure chamber acted upon by the high pressure piston, is filled with hydraulic fluid which is supplied by the pressure source.
• the high-pressure piston and with it the low-pressure piston are pushed back.
• the low-pressure piston then displaces the hydraulic fluid from its pressure chamber to the tank.
• the high pressure piston has been pushed back by a certain stroke length, it opens the opening of the control line so that the pressure of the pressure source can act on the valve spool of the control valve.
• the control valve is as Three-way valve designed.
• connection between the low-pressure cylinder and the tank is interrupted and instead a connection is established between the pressure source and the low-pressure cylinder.
• the low-pressure piston and thus the high-pressure piston are then moved again towards the high-pressure side, so that hydraulic fluid with the correspondingly high pressure can be dispensed through the high-pressure connection.
• valve slide is accordingly acted upon on the one hand by the pressure in the control line and on the other hand by the force of a spring.
• the more hydraulic fluid to be drawn off at the high-pressure connection the higher the frequency with which the booster piston on the one hand and the valve slide on the other hand have to be moved back and forth.
• the piston-cylinder arrangement can only be enlarged to a limited extent. On the one hand, this increases the time it takes to fill the high-pressure side. On the other hand, the mass becomes larger, so that a rapid reciprocating movement of the booster piston is made more difficult. This means that the delivery quantity is limited.
• the maximum delivery quantity on the high-pressure side was approximately 2.5 l / min, which corresponded to a maximum supply quantity of approximately 10 l / min and for which a frequency of 30 Hz was necessary.
• EP 0 703 369 A2 shows a changeover valve with a slide which is acted upon by a constant pressure on one side, while the other side is exposed to a pressure which is controlled by a pilot valve is.
• This Piltoventil is air-controlled and in turn is controlled by an electromagnetically controlled pilot valve.
• the object of the invention is to overcome such limitations.
• valve slide has a control disk which divides the annular space and which, depending on the position of the valve slide, is located either between the mouths of the pump line and the cylinder line or cylinder line and the tank line.
• valve slide is designed as a differential piston which is acted upon on its other side by constant pressure.
• the differential piston is therefore pressurized from the control line on one side and with a constant pressure on the other side.
• the constant pressure acts on a somewhat smaller area than the pressure from the control line.
• the valve slide Since the pressure in the control line drops from time to time, depending on the position of the booster piston, the valve slide is acted upon alternately by a force difference in one direction and by a force difference in the opposite direction. These force differences are independent of path, ie they act practically over the entire adjustment range of the valve slide bers.
• the generation of a force with the aid of a pressure can be realized simply by letting the fluid act on the end face of the valve spool with the appropriate pressure. Since the force difference is kept practically constant over the entire adjustment range, relatively high accelerations can be achieved. This can shorten the movement times.
• the frequencies with which the pressure booster works can be selected higher. This also enables a larger delivery amount of the high pressure fluid.
• the control disk divides the annular space axially, ie in the direction of movement of the valve spool. It can be kept relatively thin. The only requirement is that it provides a sufficient seal between the two axial regions of the annular space, so that either a connection from the cylinder line to the tank line or a connection from the cylinder line to the pump line is established, the tank or pump line not being connected to the cylinder line should no longer have any influence on the fluid flow into or out of the cylinder line.
• the cylinder line is connected to the low pressure area of the booster piston.
• the tank line is connected to the pressure sink.
• the pump line is connected to the pressure source.
• the pressure of the pressure source is preferably applied to the other side of the valve slide. This pressure is available anyway. It is in sufficient Dimensions constant. Additional measures are then not necessary.
• the control line advantageously opens in the stroke region of the booster piston in the high-pressure side of the piston-cylinder arrangement, the booster piston closing the control line at the start of its movement in the direction of the high-pressure connection.
• This essentially limits the pressure in the control line to the pressure of the pressure source.
• control disk completely releases the cylinder line, at least in the position in which there is a connection between the cylinder line and the tank line.
• This is the switching position of the control valve in which the fluid must be conveyed from the low pressure side of the adjusting piston to the pressure sink.
• This promotion takes place under the pressure of the pressure source, which acts on the high pressure side of the adjusting piston.
• there is a correspondingly smaller cross-sectional area of the piston, so that the emptying of the low-pressure cylinder, which is necessary for the return of the booster piston to its starting position, should not be hindered as far as possible. If the flow cross-section for the final fluid is made as large as possible or free of throttling points, this removal of the fluid can take place without problems.
• valve slide which keeps the connection of its end face free for connection of the pressure source.
• the pressure source it is in some cases not possible to connect the pressure source to the front of the valve spool in such a way that the mouth of this connection and the front actually face each other. Rather, the connection can also open laterally, ie radially into the corresponding pressure chamber. In this case, if you ensure that this mouth is always free, the pressure acting on the face of the valve spool is never throttled.
• a pressure booster 1, shown schematically in FIG. 1, has an booster piston 2 designed as a differential piston.
• the booster piston 2 is formed by a low-pressure piston 3 and a high-pressure piston 4, which are connected to one another via a piston rod 5.
• the low-pressure piston 3 is arranged in a low-pressure cylinder 6 and forms the low-pressure side together with it.
• the high-pressure piston 4 is arranged in a high-pressure cylinder 7 and together with this forms the high-pressure side.
• the cross section of the high pressure cylinder 7, ie the effective area on which pressure can act on the high pressure piston 4, is smaller than the cross sectional area of the Low pressure cylinder 6.
• the low pressure cylinder 6 is provided with a low pressure connection 8.
• the high pressure cylinder 7 is provided with a high pressure connection 9.
• the low-pressure piston 3 moves upwards under the pressure of this fluid.
• the high-pressure cylinder 7 is placed under a pressure which is higher than the pressure in the low-pressure cylinder 6 by the ratio between the cross-sectional area of the low-pressure piston 3 and the high-pressure piston 4.
• the high-pressure connection 9 is connected to a high-pressure outlet 11 via a check valve 10.
• the high-pressure cylinder 7 also has a supply connection 12 which is connected to a pressure source P via a check valve 13.
• the pressure source P can be formed, for example, by a pump.
• a control valve 14 is provided to control the movement of the booster piston 2.
• the control valve 14 is designed as a three-way valve, which connects the low-pressure connection 8 via a cylinder line 24 either to the pressure source P or to a pressure sink T, for example a tank.
• the control valve 14 is connected on the one hand to a pump line 15, which can be designed as a branch line to the line between the pressure source P and the check valve 13, and to a tank line 16, which leads to the pressure sink T.
• the cylinder line 24 is also connected to the control valve here.
• the control valve 14 has a valve spool 17 which is arranged axially displaceably in a valve housing 18.
• the valve spool 17 is also designed as a differential piston.
• the structure of the control valve 14 will be explained in more detail below with reference to FIG. 2. First of all, however, it should be noted that the pressure from a control line 19 can be applied to one end face of the valve slide 17.
• the control line 19 opens into the high-pressure cylinder 7, specifically at a point which is covered by the high-pressure piston 4, shortly after the high-pressure piston 4 has moved from its one end position in the direction of the high-pressure connection 9.
• the other end face of the valve spool 17 is acted upon by the pressure of the pressure source P.
• a further branch line 20 is provided, which opens into a pressure chamber 21 in the valve housing 18.
• the pressure chamber 21 has a smaller cross section than the bore 22, in which the end of the valve spool 17 moves, which is adjacent to the control line 19, and into which the control line 19 opens.
• a line 23 can also be provided, which connects the space between the low-pressure piston 3 and the high-pressure piston 4 to the pressure sink P.
• P corresponds to the pressure of the pressure source P
• T to the pressure of the pressure sink T
• HP to the pressure in the control line 19
• C to the pressure in the cylinder line 24, which is connected to the low pressure connection 8.
• Fig. 2 shows first of all the internal structure of the control valve 14 with further details.
• the valve spool 17 is axially displaceably mounted in the valve housing 18. Here he leaves an annular space 25 between himself and the valve housing 18 over part of its length.
• the annular space is divided by a control disk 26, which bears sealingly against the valve housing 18, into two axial areas which are sealed off from one another.
• an area of the annular space can therefore connect the mouth of the pump line 15 (P) to the cylinder line 24 (C) (FIG. 2a) or (FIG. 2d) the cylinder line 24 (C) to the tank line 16 ( T). All that is required is a movement of the valve slide 17, which corresponds to the sum of the thickness of the control disk 26 and the axial extent of the mouth of the cylinder line 24 (C). This distance can be relatively short.
• the valve slide 17 has a larger cross-sectional area (27) at the end facing the mouth of the control line 19 (HP) than at its opposite end face 29, which is connected to the pressure chamber 21 .
• the valve spool 17 is graded accordingly.
• the pressure chamber 21 also has a smaller cross section than the end face 27 of the valve slide, on which the pressure HP from the control line 19 acts.
• valve slide 17 also has a movement stop 28, which ensures that the pressure chamber 21 is always of a predetermined minimum size. This size is dimensioned so that the schematically illustrated mouth of the stub 20 is kept clear in any case. For design reasons, this branch line 20 cannot be guided into the end face of the housing 18 here. In this way, however, it is ensured that there is no throttling and thus a pressure reduction takes place. A constant force always acts on the valve slide 17 regardless of position.
• control valve 14 The function of the control valve 14 will now be explained with reference to FIG. 2 in conjunction with FIG. 1.
• Hydraulic fluid thus flows from the pressure source P via the pump line 15, the control valve 14 and the cylinder line 24 to the low-pressure connection 8.
• the low-pressure cylinder 3 is accordingly acted upon by the pressure of the pump source P and moves the high-pressure piston 4 upwards in the direction of the high-pressure connection 9.
• the control line 19 now comes into connection with the tank line 23, so that there is only tank pressure at the end face 27. Because the opposite Face 29 but is still subjected to the pressure of the pressure source P, the valve spool 17 is now moved upwards. It first interrupts the connection between the pump connection P and the cylinder connection C (FIG. 2b) and then provides a connection via the annular space 25, but this time the other section, between the cylinder connection C and the tank connection T. The valve slide 17 moves in this way long until it comes to a stop on the housing 18. All the directions given here refer to the illustration in FIG. 2. In this position (FIG. 2d), the cylinder connection C is no longer covered by the control disk.
• annular space 25 between the cylinder port C and the tank port T is enlarged, because here the thinner portion of the valve spool 17 comes into play. This results in a relatively large cross section for the flow path of the hydraulic fluid from the cylinder connection C to the tank connection T.
• valve slide Since the valve slide is acted upon by a constant pressure on its end face 29, very high frequencies can thereby be achieved, which lead to a correspondingly faster refilling of the high-pressure cylinder 7 and the low-pressure cylinder 6. This allows the delivery amount of the fluid booster to be increased.

Landscapes

• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Fluid Mechanics (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Supply Devices, Intensifiers, Converters, And Telemotors (AREA)
• Fluid-Driven Valves (AREA)
• Multiple-Way Valves (AREA)

Applications Claiming Priority (2)

Publications (2)

Family

ID=7802934

Family Applications (1)

Country Status (7)

Families Citing this family (38)

Family Cites Families (18)

• 1996
  • 1996-08-17 DE DE19633258A patent/DE19633258C1/de not_active Ceased
• 1997
  • 1997-07-05 DK DK97111400T patent/DK0825348T3/da active
  • 1997-07-05 EP EP97111400A patent/EP0825348B1/de not_active Expired - Lifetime
  • 1997-07-24 CA CA002211474A patent/CA2211474C/en not_active Expired - Lifetime
  • 1997-08-06 US US08/906,844 patent/US6295914B1/en not_active Expired - Lifetime
  • 1997-08-13 JP JP9218579A patent/JPH1078002A/ja active Pending
  • 1997-08-18 KR KR1019970039234A patent/KR100225621B1/ko not_active IP Right Cessation

Also Published As

Similar Documents

Legal Events