DE2155409A1 - Hydraulic booster - Google Patents

Description

Or. KARL FRANKE Beg.-Nr. P.

PA T f \ TA N M "A LT Dr. F / F

8 i \ ir. \ I; iiFA 90 ⁸ * ¹¹ * ¹⁹⁷¹

LORE ₁ NZOMSTiUaSE 54

Applied Power Industries, Inc. Milwaukee, Wisconsin £ 5218, V.St.A.

Hydraulic booster

BIe invention relates to a hydraulic booster with a Hydraulic cylinder in which a working piston is controlled by a Control valve is guided axially displaceably by means of pressure fluid.

The invention leads to a conversion system that uses a relatively small input force that can be entered manually, for example hydraulic servo amplification converted into a large output force, wherein the transmission ratio for a mechanical movement made with the input force on the one hand and a thereby with the output force triggered mechanical movement on the other hand is 1: 1.

The invention is based on the object for a transmission of motion in a ratio of 1: 1 for the paths to achieve a high degree of force amplification and thereby a reaction from the output side To prevent attacking opposing forces on the control input, so to absorb such opposing forces within the amplifier itself, a To enable manual emergency actuation and an exact transmission of motion without the need for a coupling linkage guarantee.

The object is achieved according to the invention in that the Working piston has a smaller first and a larger second end face, each together with the end opposite them delimit a first or a second cylinder chamber of the hydraulic cylinder, the first of which is in constant communication with the high pressure side of a pressurized fluid system, and in an axial bore a valve spindle which can be displaced coaxially thereto and which, in a first position, forms a connection between the second cylinder chamber

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and the high pressure side of the pressurized fluid system and in a second Position releases a connection between the second cylinder chamber and the low-pressure side of the pressure fluid system.

The power booster designed according to the invention sets an input side For example, mechanical movement entered with an input force of 1 to 10 kp with a travel ratio of 1: 1 into an output-side mechanical movement with an output force from, for example, 100 to 1,000 kgf; it enables, for example, the precise adjustment of a heavy load with the help of a _ wrestle control power. He is characterized by a simple and ™ robust structure that can withstand all demands in industry and conveyor technology has grown, but still allows manual actuation in the event of a hydraulic power failure. Furthermore it enables an exact transmission of motion without the aid of mechanical coupling elements, and ultimately it catches them all counterpressures emanating from a load to be moved in its servohydraulics and do not allow them to pass through to the control input. Nevertheless, the output-side movement of the load corresponds exactly to the input-side control movement in terms of size and direction of the path.

In a preferred embodiment of the invention, the first end face of the working piston facing the first cylinder chamber is half as large as its second end face facing the second cylinder chamber.

In a further development of the invention, the working piston can be at one end guided to the outside by a coaxially to it from the hydraulic cylinder Piston rod, extended for the delivery of the increased output force and the valve spindle at the opposite end of the working piston with an adjusting mechanism for introducing the to be reinforced Be coupled input force. There are both for the formation of the adjusting mechanism itself and for its coupling to the valve spindle several beneficial options. For example, the adjusting mechanism can contain a hand lever that connects to the valve spindle is connected via a control cable effective in both views.

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Instead, the adjusting mechanism can also contain a swivel lever, on which a valve rod extending coaxially to the valve spindle is articulated at a distance from the pivot bearing of the pivot lever, and one Another possibility is that the adjusting mechanism one Contains crank drive, which is coaxial with the valve spindle and screwable in an axial thread in the hydraulic cylinder threaded spindle is connected to the valve stem so that the rotary movement of the crank leads to a combined rotation and translation of the threaded spindle and thus also the valve spindle.

It is also recommended to use a swivel bearing for the hydraulic cylinder to be connected to a fixed support; this type of attachment of the hydraulic cylinder ensures, on the one hand, a sufficient abutment for the output force to be output and closes on the other hand unwanted jamming phenomena.

For the design of the working piston, a construction is preferred in the sense of the invention in which it has two in its with the second Cylinder chamber connected axial bore contains opening passages, of which in each position of the valve spindle in the bore at most one can be released and one is connected to the high pressure side of the pressure fluid system and the other to its low pressure side. In addition, the working piston can have two ring webs, which are located in the hydraulic cylinder between the first and the second cylinder chamber limit a third cylinder chamber, on the one hand with the low-pressure side of the pressure fluid system and on the other hand with one of the the two passages opening into the axial bore of the working piston are in constant communication.

For the valve spindle, a design is preferred in which it has two bearing surfaces that are in the equilibrium position of the Valve spindle shut off both passages in the working piston against its axial bore and thus against the second cylinder chamber and at Displacement of the valve spindle from this equilibrium position relative to the working piston depending on the direction of this displacement the one or the other of the passages for the axial bore in the working piston

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and thus release for the second cylinder chamber. The connection can for three cylinder chambers are made so that when the valve spindle is in equilibrium, the three cylinder chambers are all separated from each other are separated, with the valve spindle displaced, however, the second cylinder chamber depending on the direction of displacement over the axial Bore and one of the two passages in the working piston is connected either to the first or to the third cylinder caramer. Furthermore, the bearing surfaces of the valve spindle can divide the axial bore in the working piston into three valve chambers, of which the middle is in constant communication with the second cylinder chamber. The two outer valve chambers, on the other hand, are preferably in constant Connection to the low pressure side of the pressurized fluid system. These different Connections are carried out most favorably in such a way that the middle valve chamber with the second cylinder chamber is connected via a channel in the working piston, while the two outer valve chambers with each other and with the low-pressure side of the Pressure fluid system via an axial channel and a transverse bore in the Valve spindle and a passage in the working piston are connected.

To avoid any risk of the valve stem jamming In the axial bore in the working piston, the bearing surfaces of the valve spindle can be divided into several singing webs by circumferential grooves, between which then around the valve spindle the same fluid pressure prevails in each case.

In the drawing, the invention is illustrated by means of preferred exemplary embodiments, which clearly show their advantages permit; show in the drawing:

FIGS. 1 and 1A are shown schematically and partially cut away Side view of a power amplifier designed according to the invention,

FIG. 2 shows a reduced view of a first embodiment variant for the power booster of FIGS. 1 and

3 shows a reduced view of a further embodiment variant.

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The main parts of the power amplifier 10 in Fig. 1 and 1A shown are a manually actuable adjusting mechanism 12 for entering a Eingangekraft or an input motion, a via a pivot bearing 15 connected to a fixed support hydraulic cylinder * \ k and designed as a toggle lever 16 load - or working link. The adjusting mechanism 12 is of a known type and contains a hand lever 18 which can impress a long-length movement on an adjusting cable (20) which is effective in both directions.

The hydraulic cylinder 14 contains an axial bore 24 in which a working piston 26 can extend, from which a piston rod 28 is guided through an end opening 29 and a seal 30 at one end of the hydraulic cylinder ¹ Xk to the outside. At its free outer end, the piston rod 28 is connected in an articulated manner to a leg 32 of the toggle lever 16 via a pivot pin J> k. The apex 38 of the toggle lever 16 is pivotably mounted in a fixed bearing block kO via a bearing pin 4-2. The free end kk of the toggle lever 16 is connected to a load to be moved, the direction of movement of which is indicated by the double arrow A in FIG. 1A. Depending on the type and scope of the movement to be imparted to such a load, the toggle lever 16 can optionally be dispensed with and the free end of the piston rod 28 can be connected directly to the load.

The working piston 26 has two annular webs 46 and 48, which are each sealed in the bore 24 of the hydraulic cylinder 14 by means of a 0-RLngee 49 or 50 inserted into a groove machined into their circumference and thus the bore 2k in three cylinder chambers 52, 5k and 56 subdivide. Of these three cylinder chambers 52, 5k and 56, a first, namely the cylinder chamber 5k on the right in the drawing, is in constant communication with a pressure source for pressure fluid via an inlet channel 58; Pressure chamber 5k are designated. A second cylinder chamber, namely the cylinder chamber 52 on the left in the drawing, has a permanent connection via a channel 53 in the working piston 26 to an axial one that receives a control valve

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and central bore 62 in working piston 26 and will therefore be referred to as control chamber 52 for short in the following. The third and middle cylinder chamber 56 is in constant communication via an outlet channel 60 with a fluid tank, which forms the low-pressure side of the pressure fluid system, and will therefore be referred to as tank chamber 56 for short in the following. The end face A1 of the working piston 26 facing the control chamber 52 is twice as large as the end face A2 facing the pressure chamber 5k.

In the bore 62 in the working piston 26 a operates in the manner of a three-way cock valve spindle is axially displaceably guided 6k W and secured by a snap ring 99 at the open end of the bore 62 against inadvertent withdrawal. The valve spindle 6k has three bearing surfaces 7 ^ f, 76 and 78, which each lie tightly against the inside of the bore 62 and are separated from one another by shaft sections 80 and 80 with a smaller diameter. The supporting surfaces 7k , 76 and 78 delimit three valve chambers 82, 88 and 95 in the bore 62, of which the two outer chambers 82 and 95 are connected via an axial channel 96 and an adjoining transverse bore in the valve spindle 6k and the central one 88 via the Channel 53 and working piston 26 are in constant communication with the control chamber 52.

Another shaft section 63 with a smaller diameter connects the valve spindle 6k with a valve rod 70, which thus forms the coaxial continuation of the valve spindle 6k beyond the bore 62 and through the control chamber 52 and after crossing an opening 71 and a seal 73 in the piston rod 28 opposite end of the hydraulic cylinder "\ k there in a connection piece 72 terminates where it is connected to the actuating cable 20th an adjustment of the hand lever 18 thus leads via the control cable 20 and the valve rod 70 in a corresponding displacement of the valve stem 6k in the bore 62nd

The diameter of the valve rod 70 is equal to that of the supporting one Surfaces 74, 76 and 78, and the diameter of the shaft portion 63

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corresponds to that of the shaft sections 77 and 80. The valve spindle 6k is thus in pressure equilibrium with regard to the pressure prevailing in the control chamber 52, which acts in the same way on the free end faces of the valve rod 70 and the supporting surface 7k.

The supporting surfaces 7 ^ ₁ 76 and 78 of the valve spindle 6k are each provided with circumferential grooves 75ι 77a and 79, which serve to equalize pressure around the valve spindle 6k and thus prevent one-sided loading of the valve spindle 6k and thus its jamming in the bore 62 .

A passage 90 leads from the pressure chamber $ k to the bore 62, and between the tank chamber $ 6 and the bore 62 there are two further passages $ k and 98. Of these passages, the passage 98 only serves to permanently connect the two outer valve chambers 82 and 95 with the fluid tank as the low-pressure side of the pressure fluid system via the outlet channel 60. The passages 90 and Sk , however, are designed as measuring nozzles and have the same distance in the axial direction of the valve spindle 6k as the facing end faces of their bearing surfaces 76 and 78, between which the middle Valve chamber 88 is located.

When the power amplifier 10 is in operation, a clockwise or counterclockwise movement of the hand lever 18 results in a corresponding longitudinal movement for the control cable 20, which thus moves the valve spindle 6k in the bore 62 to the right or to the left.

If the valve spindle 6k moves to the right from the equilibrium position shown in FIG. 1, in which its supporting surfaces 76 and 78 block both the passage 90 and the passage 94, the passage 9 ^ remains blocked, the passage 90, however, is opened , and the high fluid pressure of the pressure source passes through the passage 90, the central valve chamber 88 and the channel 53 into the control chamber 52.B

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End face Α1 to a shift of the working piston 26 to the right. This displacement of the working piston 26 to the right continues until the passage 90 is blocked again by the supporting surface 78 of the valve spindle 6k , whereby the valve spindle 6k and the working piston 26 are again in equilibrium.

A movement of the valve spindle 6k thus leads to a corresponding displacement of the piston rod 28 by an equal distance, and the movement ratio is 1: 1. The piston rod 28 in turn causes an adjustment of the toggle lever 16 and thus the load in the desired direction and by the desired amount, with the accomplished by the manual W lever 18 induced movement of the load of the servo action of the hydraulic pressure in the pressure fluid system.

By using the illustrated power amplifier 10 in the manner described above, a contact cable 20 can be made Increase input force ten times; for example, a control force of 10 kp on the control cable 20 results in a control force of 100 kp on Knee lever 16.

If a sudden external load acts on the toggle lever 16 and leads to a displacement of the working piston 26, there is still no transfer of movement to the actuating mechanism 12 and its hand lever 18. This is mainly due to the tendency of the working piston 26 to be constantly in equilibrium relative to the valve spindle 6k , which maintains a fixed position relative to the hydraulic cylinder 14 as long as it is not displaced by the adjusting mechanism 12. If, for example, a downwardly directed load acts on the toggle lever 16, the piston rod 28 is pulled to the right. Since the valve spindle 6k maintains its position, the working piston 26 moves relative to it, and the passage 94 is released, which leads to a pressure drop in the control chamber 52 and thus to a pressure difference between the control chamber 52 and the pressure chamber 5k . The static fluid pressure of the pressure source, which flows in the pressure chamber 5k , forces the working piston 26 to the left until there is pressure equilibrium again and the supporting surfaces 76 and 78 of the valve spindle 6k shut off both the passage 90 and the passage ^ k.

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_ ₉ _ 2Ί55Α09

The distance between the passages 90 and 9h is equal to the distance between the mutually facing strips of the supporting surfaces 76 and 78. This dimensioning of the distance effectively avoids any backlash between the movement of the working piston 26 or valve spindle 6h on the one hand and the opening of the passages 90 or 9h on the other hand. In addition, the clear widths of the passages 90 and $ h are relatively small compared to the stroke of the working piston 26 5 they are, for example, 0.76 ram compared to the 5I w® stroke. As a result of this small diameter for the passages 90 and 9h and the relationship between their mutual distance on the one hand and that between the sanders of the supporting surfaces 76 and 78 on the other hand, it is sufficient to displace the working piston 26 or valve spindle Sh relative to one another by very small distances to move in the control chamber 52 to allow the full sizes for pressure loading or relief to take effect. The change in pressure in the control chamber 52 is relatively large compared to the movement distance for the working piston 26 or valve spindle 6h.

If there is a loss of pressure in the hydraulic system, when moving to the right, the control cable 20 first moves the valve spindle 6h to the right end of the bore 62 and then the piston rod 28 also to the right. When the control cable 20 moves to the left, the left end of the valve spindle Gh first comes to rest on the snap ring 99 in the bore 62, and then the working piston 26 and its piston rod 28 follow the further movement of the control cable 20 to the left. In both viewings, emergency operation with manual power is possible even if the hydraulic power fails.

In Fig. 2 and 3, two embodiment variants are illustrated, the differ from the booster shown in FIGS. 1 and 1A only in the way in which the control force is introduced.

The adjusting mechanism 120 shown in Fig. 2 has a pivot lever 122 which is mounted at one end in a pivot bearing Λ2h. In an axially extending slot 126 machined into its central part, the pivot lever 122 receives a bearing pin 128, which in turn is fixed to a valve rod leading to the valve spindle 6h

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connected is. The operation of the power amplifier of Fig. 2 corresponds to that of the power amplifier of Fig. 1 with the exception that the valve spindle Sk in Pig. 2 is displaced by pressing or pulling the pivot lever 122, which leads to a reciprocal movement of the valve rod 170 and thus the valve spindle 6k. The slot 126 enables the oscillatory or pivoting movement of the pivoting lever 122 to be converted into a reciprocating movement of the valve spindle 64. In addition, in FIG. 2 the load to be moved is directly connected to the piston rod 28, dispensing with the toggle lever 16 of FIG.

In the further embodiment shown in Fig. 3, the adjusting mechanism 270 for the valve spindle 64 has a threaded spindle 272, which can be screwed back and forth in a thread in the hydraulic cylinder 14} the combined rotary and longitudinal movement of the threaded spindle 272 in the hydraulic cylinder 14 is shared valve spindle Sk connected to it and is triggered by actuation of a hand crank of a crank drive 220 attached to the free end of the threaded spindle 272. Otherwise, the mode of operation of the booster 10 in FIG. 3 corresponds to that of the booster 10 from FIG. 1.

- patent claims -

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Claims (14)

Claims 1J Hydraulic power booster with a hydraulic cylinder in which a working piston is guided axially displaceably under the control of a control valve by means of pressurized fluid, characterized in that the working piston (26) has a smaller first and a larger second end face (A2 or A1), each of which together with the opposing them end of the hydraulic cylinder (14) a first and (54 and 52) define a second cylinder chamber, the first of which (54) in permanent communication with the high pressure side (58) of a Brück- AE stands fluid systems, and in an axial bore (62) a coaxially displaceable valve spindle (64), which in a first position a connection (90) between the second cylinder chamber (52) and the high pressure side (58) of the pressure fluid system and in a second position a connection ( 94) between the second cylinder chamber (52) and the low-pressure side (60) of the pressurized fluid system. 2. Booster according to claim 1, characterized in that the the first end face (A2) of the working piston (26) facing the first cylinder chamber (54) is half as large as that of the second cylinder chamber (52) facing second end face (A1). 3 · Power amplifier 2U | ch claim 1 or 2, characterized in that I the working piston- (2§J at one end by a coaxial to it from the Hydraulic cylinder (14) outwardly guided piston rod (28) for the delivery of the amplifying output force and extended the valve spindle (64) at the opposite end of the working piston (26) with an adjusting mechanism (12, 120, 270) for the introduction of a to be reinforced Input force is coupled. 4. Booster according to claim 3, characterized in that the Adjustment mechanism (12) for introducing the input force, a hand lever (18) which is connected to the valve spindle (64) via an adjusting cable (20) which is effective in both directions (Fig. 1). 209820/0743 5. booster according to claim 3 »characterized in that the Adjusting mechanism (120) for introducing the input force contains a pivot lever (122) on which the valve spindle (64) is coaxial valve rod (170) extending for this purpose at a distance from the pivot bearing (124) of the pivot lever (122) is articulated (Fig. 2). 6. booster according to claim 3 »characterized in that the Adjusting mechanism (270) for introducing the input force Contains crank drive (220) which can be screwed into the hydraulic cylinder (i4) via a thread that is coaxial with the valve spindle (64) and an axial thread The threaded spindle (272) is connected to the valve spindle (64) (Fig. 3). 7. Power booster according to one of claims 1 to 6, characterized in that that the hydraulic cylinder (14) has a pivot bearing (I5) is connected to a fixed support. 8. Booster according to one of claims 1 to 7, characterized in that that the working piston (26) has two passages opening into its axial bore (62) connected to the second cylinder chamber (52) (Contains 90 and 9 * 0, of which in each position of the valve stem (6 * 0 in the bore (62) at most one releasable and the one (90) to the high pressure side (58) of the pressurized fluid system and the other (94) is connected to the low pressure side (60) of which. 9. Booster according to claim 8, characterized in that the working piston (26) has two Bingstege (46 and 48), which in the hydraulic cylinder (14) between the first and the second cylinder chamber (54 and 52) a third cylinder chamber (56) limit, which on the other hand with the one (9 * 0 of the two of the working piston (26) opens passages (90 and 9 ¹ O is the one with the low pressure side (60) of the pressurized fluid system and into the axial bore (62) in permanent communication. 10. Power amplifier according to claim 8 or 9, characterized in that that the valve spindle (64) has two bearing surfaces (76 and 78) which, in the equilibrium position of the valve spindle (64), have both passages 2098 ^ 0/0743 (90 and 94) in the working piston (26) against its axial bore (62) and thus against the second cylinder chamber (52) and when the valve spindle (64) is displaced from this position of the same direction relative to the working piston (26), depending on the sighting this displacement release one (90) or the other (94) of the passages (90 and 94) for the axial bore (62) in the working piston (26) and thus for the second cylinder chamber (52). 11. A booster according to claim 9 or 10, characterized in that when the valve spindle (64) is in equilibrium, the three cylinder chambers (52, 5 ^ and 56) are all separated from one another, whereas when the valve spindle (64) is displaced, the second cylinder chamber (52) each according to the direction of displacement via the axial bore (62) and one of the two passages (90 or 94) in the working piston (26) either with the first (54) or with the third (56) cylinder chamber. 12. Power booster according to claim 10 or 11, characterized in that that the bearing surfaces (76 and 78) of the valve spindle (64) the axial bore (62) in the working piston (26) in three valve chambers (82, 88 and 95), of which the middle (88) is in constant communication with the second cylinder chamber (52). 13. booster according to claim 12, characterized in that the two outer valve chambers (82 and 93) i ^ß permanent communication with the low pressure side (60) are the pressure fluid system. 14. Booster according to claim 12 or 13 «characterized in that the middle valve chamber (88) is connected to the second cylinder chamber ( ^ 2) via a channel (53) in the working piston (26) , while the two outer valve chambers (82 and 95 ) are connected to one another and to the low-pressure side (60) of the pressure fluid system via an axial channel (96) and a transverse bore (97) in the valve spindle (64) and a passage (98) in the working piston (26). 209820/0743 15 · Power amplifier according to one of claims 1 to 1 * t, characterized in that that the bearing surfaces (76 and 78) of the valve stem (6 ^) by circumferential grooves (77a or 79) in several Entrances are divided. 209820/0743 Blank page