DE8005916U1 - HYDROSTATIC TURNING PISTON - Google Patents

Description

Most rotary lobe hydrostatic pumps and motors use a rotary valve to provide fluid flow to and from the cylinders controlled, which is composed of a fixed component with one or more feed openings and one or more return ports, and from one Rotary body or rotor, in which the ducts to the cylinders lead from rotor openings that are calibrated to the stationary ones Open openings periodically depending on the working cycles of the pistons. Both in the upper and Even in the bottom dead center positions of the pistons, the rotor openings are through the land areas of the stationary ones Openings separating bridges are closed, these closures creating the necessary separation points or delimitations between the high and low pressure phases of the piston work cycles. The fixed openings, where there is high pressure, alternate with fixed ones

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Openings where there is low pressure, and the land areas between adjacent fixed ones High and low pressure ports generally overlap in the piston dead center positions on either side of each rotor port with the web areas of the valve rotor located between the rotor openings to prevent leaks between the Keep high and low pressure openings as small as possible.

Although for hydrostatic rotary piston machines (pumps and motors) there are many suitable rotary valve systems -, in

s- in some cases the overall machine design may make the use of certain types necessary - a valve system that is particularly advantageous for a variety of machines has a central, fixed, cylindrical pin or bearing shaft with feed and return channels that open into inlet and outlet areas, which are separated from one another by a diametrical wall and open to the outside via relatively large inlet and outlet openings. A rotor with a plurality of cylinders, each of which is connected by a channel to a rotor opening which opens on an inner, cylindrical surface, is rotatably arranged on the bearing shaft so that the rotor openings sweep over the openings in the bearing shaft. Diametrically opposite one another at the bearing

C de bridges close each rotor opening in the dead center positions of each piston. The valve configuration described above is advantageous for machines in which each piston performs a complete working cycle during each revolution of the rotor. A complete machine (pump or motor) with a valve in approximately the embodiment described above is known from US Pat. No. 3,709,104.

The special design of the valve assembly of hydrostatic Rotary lobe pumps and motors pose several difficulties. In theory, it should be the largest hydraulic Efficiency by keeping the rotor openings open at all times,

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except at the top and bottom dead center of the piston, to be attainable, whereby the entire supply and return of fluid Cylinder content of each cylinder is used. In practice, the performance level is greatly reduced by the Leakage between the bridge between the fixed openings and each rotor opening in and near the dead center positions and is therefore generally impractical. A leakage reduction and an improvement The efficiency is generally achieved by increasing the width of the bridge on either side of the Rotor opening dead center achieved, whereby on both sides of each rotor opening dead center position overlaps between the land areas of the fixed valve component and the rotor are created, which form sealing zones, which limit the passage of fluid.

An improvement in the level of performance by creating overlaps aimed at reducing the leakage At the bridges, however, there is increased cavitation and both hydraulic and mechanical noise at the expense of which results from the pressure pulses generated by the piston adjustment when the rotor opening is closed will. The cavitation and noise problem takes several forms. Perhaps the most serious impact occurs at the beginning of the suction stroke of a pump: the piston tries to draw in fluid while the rotor is opening is closed, and instead creates a vacuum and consequently cavitation and the associated noise. Other Examples of important effects of occluding a rotor opening are

1) with a pump and piston adjustment near the end the suction stroke closed openings: cavitation, hydraulic noise and energy loss;

2) with a pump and piston adjustment with the opening closed near the beginning and end of the discharge stroke: pressure pulse, This leads to the development of both hydraulic and mechanical noise and loss of energy

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as a result of additional work that must be applied in order to compensate for the piston displacement fluid through the To push through overlapping points;

3) with an engine and piston adjustment / near the beginning or End of the working stroke (high pressure supply) closed opening: pressure drop in the cylinder with possible cavitation and noise generation; Loss of energy because the fluid on the piston is not "working";

4) with a motor and piston adjustment close to the beginning or end of the discharge stroke (low-pressure return) closed opening: pressure pulse (because fluid is trapped is); hydraulic and mechanical noise; Loss of energy through work on the enclosed fluid.

The extent to which overlaps adversely affect efficiency and lead to cavitation and noise is on the degree of overlap and on the size of the play between the fixed valve component and the rotor. if the amount of overlap is reduced, the clearance is increased, or both, cavitation and noise are reduced, however, the leakage increases and everyone gains in Overall efficiency as a result of a longer effective piston stroke can be due to a reduction in the efficiency increased leakage can be compensated.

In US-PS 1 964 244 it is proposed to completely omit overlaps on the entry side of each bridge and only on the exit sides * It is at best questionable whether the zero overlap in view of the greater leakage and the equally large loss of power represents the best overall design. In addition, the direction of work are not reversed, so that the proposed solution contained in US Pat. No. 1,964,244 generally only applies to pumps is applicable

The invention creates a valve system for a hydrostatic rotary piston machine (pump or motor), the cavitation and

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Noise significantly reduced, an effective seal made possible by large overlaps and thus Keeps the loss of efficiency due to leakage as low as possible, and the efficiency through a More effective use of the sections of each piston stroke improved with the overlap of the rotor openings the bridges collapse.

According to the invention openings are formed during selected Periods or during all periods of the piston strokes in which the rotor opening is closed by a bridge , -, is, except in approximately the top or bottom dead center, connect each cylinder to the supply and / or return area. In particular, one or more openings stand for any or all of the OperationsB listed below to disposal:

1) one for the initial portion of the fluid delivery stroke or more openings connecting each cylinder to the feed area while after leaving the lower one Dead center, the associated rotor opening is closed by an overlap on the exit side of a bridge is;

2) Fürten last section of the Pluid-feeding stroke or a C more openings which connect each cylinder to the supply area, while the associated rotor opening is closed by an overlap at the entry side of a bridge before reaching the top dead center;

3) for the initial section of the pluid return stroke one or more openings connecting each cylinder to the return area while leaving the upper one Dead center, the associated rotor opening is closed by an overlap on the exit side of a bridge is; and

4) for the last section of the pluid return stroke, one or more openings connecting each cylinder to the return area

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connect if before reaching top dead center the associated rotor opening is closed by an overlap on the entry side of a bridge.

Each of the foregoing orifices is designed to provide a fluid flow rate that is not less is than the rate which, with the rotor opening closed, of the displacement during the relevant stroke section is required. This repression and the duration of the

opening closure can be calculated without difficulty,

II and on the basis of this, with the help of normal Fluidic

S, - ', Flow equations determine orifice dimensions that produce the necessary flow rate. It is also advantageous if the flow rate does not greatly exceed that which is required by the displacement during the opening closure. . ■■

While the openings can be formed in the rotor, it is easiest or least expensive to do so Holes can be drilled in the bridges. In general, openings represent all four of the operating conditions mentioned above to disposal.

The openings cause a considerable reduction in Noise and cavitation due to the constant flow of fluid to and from the cylinders during each work cycle, whereby steep-edged pressure pulses or hard pressure surges are alleviated or practically eliminated. The openings can be designed to limit the rates of pressure changes occurring between the supply and return phases and in each case produce smoother transitions between high and low pressures. The game between the camps and the rotor can be designed solely for sealing and lubricating effect rather than a compromise to achieve the required leakage between the cylinders and the feed and return areas of the bearing shaft. This is a particularly important advantage for low-speed high-pressure

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Machinery. Because the cylinders during the feed strokes are kept filled and can be emptied during the return strokes, the energy losses are reduced without that the seal is adversely affected. The openings do not increase the leakage to a significant extent, as they are small, provide flow rates approximately equal to displacement, and are spaced from one another arranged, which is not smaller than the corresponding dimension of each rotor opening.

Embodiments of the invention are explained in more detail below with reference to schematic drawings. It shows:

Pig. Figure 1 is a side view of the valve part of a bearing shaft provided with openings in the bridges is,

the cut 2-2 in Pig. 1,

a section of a bearing shaft and a rotor in section 3-3 in Pig. 4,

the section 4-4 in "Pig. 3,

a portion of a bearing shaft and an apertured rotor at section 5-5 in Pig. -6 and

6 shows section 6-6 in Pig. 5.

The one in Pig. 1 and 2 is shown, for example, in a pump or motor of that in US Pat. No. 3,709,104 described and shown type usable and has a cylindrical valve part, in which from one end four large holes 10, 12, 14 and 16 extend into it. The two holes 10 and 12 go from a pluid supply line, not shown while the other two holes 14 and 14 lead back to a return line, not shown. At the Valve part, recesses 18 and 20 are separated from one another by a diametrical partition 22. The recess 18 is a

/8th

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Feed area and on the periphery of the bearing stock by a Feed opening 24 is limited, while recess 20 is a return area and is delimited by a return opening 26 is. The side edges of the supply and return openings 24 and 26 in the bearing shaft delimit bridges 28 and 28 30, which are arranged symmetrically on opposite sides of the bearing shaft on the sides of the partition wall 22. Longitudinal webs 32 and 34 at right angles to the partition 22 stiffen the valve part.

Referring to Figs. 3 and 4, the in Pig. 1 and 2 shown / - show the bearing shaft, the valve part of the bearing shaft, a rotor 36 is arranged, which surrounds a bearing shaft of the cylindrical block 38 and a plurality of radially oriented cylinders 40 is composed, are drawn from those five. Pistons (not shown) can be moved back and forth in the radial direction in the cylinders 40. If it is a pump, the pistons can be driven during the working stroke by a reaction assembly, not shown, which is arranged eccentrically with respect to the axis of the bearing shaft and the rotor 36 If it is a motor, the pistons drive the said reaction assembly on the working stroke. The axes of the reaction assembly and the bearing shaft are arranged in a diametral plane C, the bridges 28 and 30 cut in half; the top and bottom dead center positions of each piston therefore arise when the axis of the corresponding cylinder lies in this plane. For example, if the axis of the reaction assembly according to Fig. 4 is arranged to the left of the axis of the bearing shaft, each piston is in the upper dead center designated OTP, when the cylinder axis passes through the 9 o'clock position, and in the lower dead center UTP, when the cylinder axis goes through the 3 o'clock graduation. When each cylinder rotates, in the example shown, counterclockwise from the UTP to the OTP position, fluid enters through a rotor opening 42 in the inner bore of the rotor block 38 and becomes an inlet and outlet channel 44 to the cylinder 40

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directed. The feed stroke ends and the return stroke begins, at top dead center OTP, with the piston on its way moved back from top dead center OTP to bottom dead center UTP towards the bearing stock.

Different surfaces of the recesses 18 and 20 formed supply and return areas of the bearing shaft, the openings of the bearing shaft and the rotor openings 42 and the inlet and outlet channels 44 of the bearing shaft and of the rotor 36 'which are shown in the drawings are shown in FIG designed in the same way as in certain embodiments, / which are described and shown in DE-OS 28 52 991. The shape of the openings and channels ensures a uniform, relatively turbulence-free flow and from the cylinders 40 for smooth, efficient operation.

The bridges 28 and 30 are slightly wider than the rotor openings 42, and the ends of the rotor block 38 extend in the longitudinal direction somewhat beyond both ends of the rotor openings 42 and the supply and return openings 24 and the bearing shaft. The overlaps in the width and length direction between the rotor bore and the bearing shaft create a seal around the rotor openings Γ 42 and the feed and return openings 24 and 26, since the small radial play and the large (relative) lengths of the overlaps make the pluidstrow strong restrict. Some leakage is inevitable and actually necessary for lubrication between the rotor 36 and the bearing shaft. The invention allows the sealing and lubrication to be optimized through the design of the clearance and the bridge width without having to worry about cavitation and the generation of noise caused by the closure of the rotor openings 42 when the pistons are moving.

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In the embodiment according to FIGS. 1 to 4, two inlet and outlet channels or openings 46 and 48 or 44 and 50 are arranged in each of the bridges 28 and 30 so that, when the associated cylinder 40, the UTP or Takes the OTP position, symmetrical to the top dead center OTP and bottom dead center UTP and at a distance from the plane OTP-UTP slightly outside the edge of the associated rotor opening 42, the rotor openings 42 are therefore completely closed in these positions. During a period of time that is dependent on the bridge width, the rotor openings 42 are closed from the bottom or top dead center UTP or OTP to both sides {- , by the bridge 30 or 28, but fluid can, depending on the case, through the Openings 44 and 50 or 46 and 48 flow to or from the supply or return areas which are formed by the recesses 18 and 20. The flow rate through each orifice 44, 46, 48 and 50 for a given fluid viscosity, pressure drop, and machine speed is a function primarily of the length and diameter of orifice 44, 46, 48 or 50, and the length and diameter can be determined mathematically that the flow is exactly matched to the cylinder contents between the lower or the upper dead center UTP or OTP and the opening of the feed and return openings 24 and 26 of the bearing shaft towards the rotor openings 42.

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Instead of a single opening 44, 46, 48 or 50 on each side of the rotor opening 42 when it is in the OTP or UTP position occupies, can on each side with different circumferential distances from the plane UTP-OTP several openings of the same or of different dimensions, in order to prevent the rotor opening 42 from being closed by the bridge 28 and 30, respectively, to produce a variable flow rate to and from the cylinders 40; the further the rotor opening 42 from dead center removed, the greater the number of exposed openings, and vice versa. By forming the openings with different dimensions, in different numbers and in different places can be found on the entry and exit sides

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of the bottom and top dead center TJTP or OTP fulfill various current control tasks.

When the bearing shaft and rotor 36 according to FIGS. 3 and 4 in If a pump is installed, openings 44, 46, 48 and 50 have the following effects:

1) During the time in which a cylinder 40 from the bottom dead center UTP corresponding position moves into the position that the opening of the corresponding rotor opening 42 corresponds to the feed area 18, fluid can flow into the cylinder 40 through the opening 44. Cavitation

(^ and noise caused by the suction of the piston when the rotor opening 42 is closed are greatly reduced or eliminated.

2) From the closure of the rotor opening 42 by the bridge 28 to the top dead center OTP, the opening 46 Fluid flow from the supply area or the recess 18, with essentially the same effect as under (1).

3) A cylinder 40 which moves from top dead center OTP to the position in which it moves to the return area or opens towards the recess 20, can release fluid through the opening 48 and is not subject to the hard pressure surge,

C which would occur if the piston were to work against a completely closed rotor opening 42. Hydraulic and mechanical noises are greatly reduced, and the piston does work.

4) In the case of a cylinder 40 that is out of the position with locking moved through bridge 30 to bottom dead center UTP, port 50 releases fluid to the return area or the recess 20 of the bearing shaft, with the same advantages as stated under (3) above.

In the case of an engine, fluid under high pressure can be drawn from the supply area and from the Recess 18 in each cylinder 40 during the periods

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flow, in which the rotor ports 42 are closed by the bridges 28 and 30, however, _f do not occupy the UTP or OTP-position. The fluid does a useful job and cavitation and noise caused by piston movement in a closed cylinder 40 are significantly reduced. The backflow of fluid through the opening 48 begins as soon as a cylinder 40 leaves the position corresponding to top dead center TDC, and there is no noisy, lossy "shock" against a trapped, high-pressure fluid. In a similar way, from the closure of the rotor opening 42 by the bridge 30 to the position corresponding to the bottom dead center UTP, a uniform return flow through the opening 50 continues.

During each partial stroke between the closing of a rotor opening 42 and one of the dead centers, the fluid flow through the associated opening 44, 46, 48 or 50 corresponds exactly to the requirement resulting from the piston displacement or displacement. Minor amounts of fluid to pass through to the leakage sites, as required by the cylinders 40, no fluid "is * ¹ The machine operation is softer and more quiet;. The efficiency is increased and the seal is optimized, since at the point of contact between the rotor 36 C and Bar areas of the bearing shaft for the fluid flow from the high to the low pressure area are no short paths available.

FIGS. 5 and 6 show a modified embodiment in which the openings are formed in the rotor 36 instead of in the bearing shaft are. This is of course a little more expensive, as many more holes are drilled in less accessible places Need to become; in terms of the results, however, this solution is equivalent. Each cylinder has two openings 52 and 54, which extend obliquely from it in opposite directions and on the rotor bore on such Places that they open when the cylinder at the top or

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lower dead center OTP or UTP is applied, are arranged exactly on the inside at the edge of each bridge 28 and 30, respectively. From the different Apart from the location of openings 52 and 54, that is in Pig. 5 and 6 are the same as the embodiment shown the embodiment according to FIGS. 1 to 4 »works in the same Way like this and brings the same results.

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SUMMARY

Openings either in bridges of the bearing shaft or in the rotor of a hydrostatic rotary piston machine (pump or Motor) connect each cylinder to the feed and return areas of the bearing shaft during the sections of each cylinder work cycle in which the cylinder openings are otherwise closed by the bridges, but do not assume the dead center positions. The openings control the Pluid flow to and from each cylinder causing cavitation, fluid noise and mechanical noise to set in O as little as possible, caused by the pressure impulses or bumps caused, which would otherwise occur if the cylinder openings to during the piston adjustment would be completely closed on leaks on the bridges. This creates an optimal seal on the bridges is made possible, and by reducing the pressure pulses with the aim of a smoother run during the whole Each piston working cycle is also an improvement. of efficiency achieved.

Claims (6)

■ .- .. UK.-ΙΚύ. 1 > Λ \ Ζ ί l'l MIKlFP WUESTHOFF-v. PECHMANN-BEHRENS-GOET2 DIFL.-CHEM. DK. E. FREIHEAR OF I ¹ ECHMAN) PROFESSIONAL REPRESENTATIVES BEFORE THE EUROPEAN PATENT OFFICE DR.-INC. DIETER BEHRENS UANDATAIRES AGRe £ s PRES!. 'OFFICE EUROPEEN DES BXEVETS DIFL ₁ -ING .; DIPL.-TIRTSCH.-ING. RUPERT GOE D-8000 MUNICH SCHWEIGERSTRASSE 2 phone: (089) 66 20 ρ TELEGRAM: PROTECT PATENT Telex: 524070 1 _G -52 167 '■ "■■ .-. Protection claims: • - ■, 1. Hydrostatic rotary piston machine (pump or motor) ^,! that is, a storage area for supply and return areas Has fluid which open out at openings separated from one another by bridges, and a rotor has several cylinders in each of which a reciprocating piston is received and one after the other via rotor openings with the openings connected in the bearing shaft and periodically from "the openings in the bearing shaft by closing the rotor openings be separated by bar areas of the bridges, and each of the bar areas to achieve a good * Sealing has a considerable overlap with web areas of the rotor, thereby g e k-e nnzeich that at least one opening (44,46,48,50; 52,54) each cylinder (7x (40) with an area on the bearing shaft during approximately the the entire duration of one or more of the periods of the corresponding piston strokes, namely a) with the feed area (recess 18) from the closure of the rotor opening (42) to the top dead center (TDC) of the Piston, but this excluded, b) with the feed area (18) from bottom dead center (UTP) of the piston, this excluded, however, until the opening of the rotor opening (42) to the feed area (18) of the bearing shaft there, - - c) with the return area (recess 20) from the closure of the rotor opening (42) to the bottom dead center (UTP), this excluded, and - 2 - 52 d) with the return area (20) from top dead center (TDC), although this is excluded, until the rotor opening is opened (42) towards the return area (20). 2. Hydrostatic rotary piston machine (pump or motor), with a warehouse supply and return areas for Has fluid which open out at openings separated from one another by bridges, and a rotor has several cylinders in each of which a reciprocating piston is received and one after the other via rotor openings with the openings associated in the camp and periodically by the .— ·. Openings in the storage facility by closing the rotor openings be separated by web areas of the bridges, and each of the web areas to achieve a good Sealing has a considerable overlap with the web areas of the rotor, thereby g e k- e nnzeich that Openings (44,46,48,50; 52,54) of each cylinder (40) one after the other with the feed and return areas (recesses 18, 20) of the bearing shaft during approximately the entire period of each piston stroke when the associated cylinder opening (rotor opening 42) through a web area of a Bridge (28,30) closed and the piston is not in top or bottom dead center (OTP or UTP). C 3. Rotary piston machine according to claim 1 or 2, characterized in that each opening (44, 46, 48, 50) passes through one of the bridges (28, 30) of the bearing shaft. 4. Rotary piston machine according to claim 1 or 2, characterized in that each opening (44,46,48,50; 52,54) is so dimensioned that its fluid flow rate is not less than the rate that is sufficient to during a such period of each piston stroke the cylinder (40) to supply or discharge an amount of fluid that corresponds to the The cylinder content of this cylinder (40) is the same during this stroke period. • ■ • a 1 - 3 - 52 167 5. Rotary piston machine according to claim 4, characterized in that each opening (44,46,48,50; 52,54) is so dimensioned that its pluid flow rate is not significantly greater than the rate that is sufficient to during during such a period of the piston stroke the cylinder (40) to supply or discharge a quantity of fluid that corresponds to the cylinder contents this cylinder (40) is the same during this working cycle period, to thereby avoid losses due to leakage to be kept as low as possible. 6. Rotary piston machine according to claim 4, characterized ^ - characterized in that each opening (44,46,48,50) penetrates one of the bridges (28,30) of the bearing shaft.