DE1403935A1 - Gear pump or gear motor - Google Patents

Description

KxessbrAjan - avB ". I

Gear pump or gear motor

The invention relates to gear pumps and gear motors, in which several gears can be rotated in one housing are stored and constantly comb with each other.

With these it was previously necessary in principle that to hydraulic separation of the one that meshes with each other during operation Side of the meshing inflow area from the outflow space lying on the meshing side of the tooth engagement apart from the flank contact of the singriff standing teeth the individual gears from the housing both on their end faces and on their tooth tip surfaces (on the circumference of the gear) must be encompassed with very tight running play.

Despite the precise machining of the housing that is necessary as a result the gear pumps are relatively cheap and, above all, reliable and low-wear. One is therefore increasing endeavors to use gear pumps and gear motors also in so-called oil hydraulics. With the ruling there Tendency towards the lowest possible viscosity and high pressure of the medium to be conveyed, unfortunately, even with precision gear pumps, their internal leakage losses increase so much suggests that as the delivery pressure increases, the delivery rate of the pump decreases to an inadmissible degree and, moreover, a unwanted strong heating of the working medium (e.g. oil) entry.

Known improvements had about the destination, the above-mentioned internal leakage up to reduce a useful measure * this, the gap widths between the housing and the gears would have adapted to the particular delivery pressure

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will. In this sense, e.g. known as "the two housing walls resting on the face of the gears be replaced by special axially movable cover body, which by appropriate structural precautions from the respective Working pressure itself can be printed with such force against the gearwheel end faces that there is only a great deal small gap losses are possible. Unfortunately, however, the circumferential seal, which is always necessary for the gears, means that the aforementioned movable sealing body is exactly the spectacle-shaped one Profile of the gear pump housing cross-section must and must also have adapted circumferential shape these either fitted directly into the pump housing with an extremely precise fit or by additional ones Sealing means, which are also not easy with the complicated circumferential shape, can be sealed axially movably. While the sealing problems just mentioned on the end faces of the gears are still usable technical solution are accessible, is the equally necessary improvement of the circumferential seal on the gears a problem that has not yet been resolved.

The invention now aims to solve the existing sealing problems in a comprehensive manner and it achieves the same by a fundamentally new design of the whole gear pump, by a special arrangement of the gears it is achieved that the circumferential seal of the gears is completely superfluous in the housing. The main feature of the gear pump according to the invention forms one or more, respectively Self-contained chain chains consisting of at least four toothed wheels, the toothed wheels of which are arranged in such a way that that the two tooth engagements of each gearwheel take place on a pitch circle diameter of unequal size.

If such a chain of wheels is frontal from the housing or Means equivalent to it are covered and rotated, so do those that are immersed unequally deeply into one another

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Teeth depending on the direction of rotation a transport of the wheel chain ' surrounding medium according to that of her and the frontal Top surfaces enclosed cavity or vice versa.

A gear pump according to the invention has the "impressive advantage, that with her no circumferential seal or tooth head seal of the wheels is necessary and therefore the housing is no longer the one required for the gear pumps that were customary up to now Must have glasses-shaped recess. It can encompass the wheels with a large spacing and the gears End-to-end sealing flat surfaces of the housing can reduce the G-Ieitflache and thus also the friction losses can be largely reduced.

The advantages of the new gear pump only come into their own when, according to a further proposal of the invention and based on already known principles also with her the frontal sealing of the gears Wheel chain through at least one axially movable sealing plate happens. In contrast to the sealing bodies of the previous gear pump already mentioned above, the same can be used in the new pump because of the lack of a circumferential seal Make the gears much easier and cheaper. According to the invention, the sealing plate is only dimensioned so large that that they are only little more than the tooth sections and the tooth meshing that protrude into the space enclosed by the toothed wheel chain zones and is supported by at least one piston-like and acted upon by the respective delivery pressure and on the housing wall or the like. supportive means so in Direction against the gear is loaded so that it always has the low contact pressure necessary for sealing. " The elimination of the complicated circumferential seal in connection with the or the very simple heart & dividing cylinder; shaped pressure piston has significant manufacturing needs and therefore also price advantages. :

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It had "previously been assumed that" in the new 'gear pump, the gears of the wheel chain stationary but rotatable in the Housing are mounted and in such a design it corresponds in its external effect to the normal previous gear pump with a certain throughput / revolution. In perception However, the invention makes the door strike, at least every second but one load of the chain of wheels to be mounted radially displaceable in such a way that the two pitch circle diameters effective in each case are continuously variable and always allow them to be adjusted in opposite directions. This allows the throughput / revolution in one from Hull to a certain maximum conveyance determined by the kinematic conditions of the gears adjust. Advantageously, according to the invention, the possibility of radial displacement of the gears indicated above is advantageous even expanded so far that one goes beyond the middle position and extends to the opposite kinematic The limit of the gearing is expanding radial displacement. This structural measure achieves that the new gear pump is a stepless going from a central position with Uullförderung in both directions Adjustment of the throughput in both conveyor belts or a total control of the flow rate allows.

No special explanation is required that the new tooth, wheel pump can also be operated as a gear motor or alternatively as a pump or motor. That is also according to the invention at least four-wheel closed gear chain; not to a certain type and size of the gears and also not tied to a specific arrangement of the same. It can, for example, easily consist of spur gears as well a combination of internally and externally toothed gears and finally also consist of bevel gears. The principle of the invention of the closed wheel chain as a displacement machine element can also be an extension of the

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Chain of four gears to an even higher one Number of gears and a logical combination of gears to form a structure that contains several closed gear chains, which either allow several separate and independently adjustable flow rates or partially or are summarized completely lau a controllable total flow rate. All gear pumps built according to the principle of the invention always have the most important feature of the invention in common, namely gears, which are on the tooth tip or circumference run freely in the housing at a large distance.

Examples of the subject matter of the invention are shown in FIGS. 1-5.

It shows:

Pig. 1 a gear pump with the housing cover removed, Pig. 2 the same gear pump in vertical longitudinal section, Pig. 3 the same gear pump in horizontal longitudinal section, Pig. 4 the scheme of a 6-wheel gear pump, Pig. 5 the scheme of a 6-wheel gear pump in the form of a planetary gear.

Parts with the same effect have the same reference symbols in all figures.

In the gear pump shown in Pigl 1, the driving gear 2 with the drive shaft and a further gear 4 are fixedly and rotatably mounted on a bearing pin 5 in a housing 1 with a housing cover 1 ′. The latter is inserted in an oil-tight manner into matching bores in the housing 1, 1 via its end pin. Cross bolts and other, not drawn screws connect the housing 1 and the housing cover 1 ^f to form a rigid box. The housing cover 1 'has a central cylindrical recess 7 for receiving a piston-like extension 8' from a rocker 8, which is guided in the housing in a radially stationary but axially movable and pivotable manner. In the approach 8 * a ring groove is cut into which a sight element, for example

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wise a so-called O-input 9 is stored and for the "Good sealing of the extension 8 · in the recess 7 ensures. The rocker arm 8 has the housing center axis on both sides or its axis of rotation has a bearing pin 10 fixed in it and a gear 11 is rotatably mounted on each of these. The gears 11 are with the other two gears 2 and 4- in permanent meshing. The rocker 8 can from the outside, for example from a lever 12, over a centrally mounted in the housing 1 and rotatably connected to it via a toothing control shaft 13 of a with the horizontal image axis X-X (see Pig. 1) coinciding central position from in both directions of swivel around an angle ρ be pivoted. The side of the housing 1 and the rocker 8 facing the gears is roughly the four Tooth meshing area exactly plan so that the by the gears 2, 4 and 11 framed space 14 largely sealed off, but via the central bore 15 of the Rocker 8 and axial bores 16 of the control shaft 13 Fixed or one-piece toothed disk 17 in hydraulic connection with the connection bore 18 of the housing 1 stands. In addition, the gears 2, 4 and 11 are clad by the housing 1 with a considerable distance from the wall and thereby The cavity 19 given in the housing 1 has an outwardly leading connection bore 20.

The mode of operation is as follows: With a driven shaft 3 and the center position of the adjusting shaft 13 and with the rocker arm 8, all gear wheel bearings have the same axial distances under calibration and with it the four gears mesh with the same size operating pitch circles. As at the entry points of the closed gear chain with an even number of teeth The same number of pairs of teeth approach the enclosed cavity as they move away from it, remains the same same working diameter diameter of the tooth meshes the volume of the working pressure enclosed by the gears and to be supplied or discharged via the connection holes 18, 20

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mediums (e.g. oil) -constant. The gear pump forms in this Control position for the working medium only a flow lock. But as soon as the rocker 8 is pivoted out of the neutral middle = HuIl position on the adjusting lever 12, in Pig. 1 e.g. clockwise, all the wheels of the gear chain get to achieve a degree that increases with the swivel angle Funding necessary unequal operating pitch circle diameters at both points of contact. The resulting demand direction is always determined by the direction of rotation of the gears and, at the same time, by the pivoting direction of the rocker arm 8.

For safe and adequate sealing of the gearwheels enclosed seam opposite the remaining cavity 19 of the housing 1 is a tight contact of the gears on the housing wall and an equally tight contact between the rocker arm 8 and the gears is necessary. The now acts to secure the same respective delivery pressure depending on the delivery direction either to the outside of the piston-like extension 8 'lying part of the rocker 8 or on the piston-like extension 8' of the rocker itself always in such a way that with correct dimensioning the pressing hydrostatic forces outweigh the hydraulic forces lifting the rocker so far that at the end faces of the Gears just have the minimum necessary lubricant film thickness preserved. The one exerted by the rocker arm 8 on the gears Axial thrust is then also effective on the opposite end faces because the gears are on their bearings are axially displaceable.

The principle of the cover plate hydrostatically loaded by the delivery pressure (== differential pressure between the medium pressure at the inlet and outlet of the pump) to cover the cavity enclosed by the gear chain is of course not tied to the embodiment shown. It may, for example to achieve a certain axial adjustment of the drive shaft 3, or to dispense material when housing good Gleiteigenacnaften without further the rocker 8 on both tooth

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be arranged wheel sides, so that the axial freedom of the same also the whole gear set benefits or that the whole gear set is axially after the driven gear can align. It is also not absolutely necessary for the rocker 8 to have only a single piston-like effect Approach 8 'to lead and to be pressed. In addition to this or sagar instead of this several such hydraulic Pistons can be arranged distributed over the entire surface of the rocker arm 8. Besides, the principle of the invention is finally not at all tied to the radially displaceable mounting by means of a rocker. The one for the stepless Adjustment and reversal of the delivery rate, the necessary radial displacement of the gears provided for this purpose could, for example also take place by means of a bearing of the same on their part rotatably mounted in the housing 1 eccentric shafts.

4 shows a further schematic representation Possibility of training the gear pump within the scope of the principle of the invention. Since the important individual parts have the same designations as those shown in Figures 1-3 Example, it is sufficient to point out without special explanations, that here the gear chain consists of six gears and, for example, the rocker 9 of Fig. 1 is simple has to have three bearing bolts 10. The center lines shown indicate the swivel range of the rocker arm.

FIG. 5 also shows a further example of the invention in a purely schematic representation. Here has the gear pump the gear arrangement of a planetary gear, whose over his Drive shaft 3 driven sun gear 22 via the planet gears

and 23 '
23 is in engagement with the internally toothed ring gear 24.

The drive shaft 3 and the ring gear 24 are in a housing, 1 stationary stored. In contrast, all planetary gears 23 are dimensioned in the toothing and mounted in the housing 1 so that they can be moved radially. There are a total of four four-wheeled wheel chains and, accordingly, only four of Gears and the two cover plates (designed as a ring plate and not shown) enclosed pump rooms, each of which can be effective separately. As long as the planet gears

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23 and 23 'are on the same pitch circle, they all rise Yerdranger effects on and only the passage is blocked. However, as soon as the two gear wheel pairs 23 and 23 ′ formed from gear wheels lying diametrically opposite one another are unequal center-to-center spacing have from the central axis of the sun gear 22, for example, cavities A form as the amount of medium increases and cavities B with decreasing amount of medium. The delivery rate is of the differentiating center distances, the conveying direction except for the direction of rotation of the sun gear 22 thereof depending on which of the teeid pairs of wheels (see above) is the larger Having center-to-center distance. It is immediately clear that here too the two pairs of wheels have no effect on the principle of the pump 23, 23 'in the housing (not shown) can be continuously adjustable radially (for example by means of Eccentric or the like) and then this pump is reversed as well as being steplessly adjustable in both conveying directions. Likewise, no further explanation is required that here too the lateral cover of the pump cells can be done by hydrostatically loaded, axially movable cover plates. Worth mentioning is finally that, as in the examples shown in Figures 1-4, the number of gears per Cell or chain of wheels exceed the minimum number of 4 and each can be any number divisible by two, further that in an arrangement according to example FIG. 5, the number of planetary gears 23 can be at least two or any larger.

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Claims (1)

Claims Gear pump or gear motor, in which several gears are surrounded by a housing, characterized in that the or the same one or more each- '" Weil consists of at least four toothed wheels, has self-contained wheel chains, the toothed wheels of which to achieve a displacement = conveying effect so arranged or stored in the housing that the two Tooth engagement of each individual wheel of the wheel chain (s) a certain or adjustable difference in Have operating pitch circle diameter. Pa 1100 009818/0664 -11 -_ Blank page