DE3119994A1 - Hydraulic axial piston variable displacement pump - Google Patents

Abstract

The invention is intended for use in machines designed for various purposes having a hydraulic drive, in which hydraulic axial piston variable displacement pumps are used, for example in hydraulic excavators. The hydraulic pump contains a housing, in the internal chamber of which a drive shaft is accommodated, which shaft is connected via a disc, connecting rods and pistons to a cylinder block arranged at an angle to the drive shaft, which cylinder block is supported by way of a moveable distributor (8) against the housing cover. The gudgeon pin of a power piston projects into the bore of the distributor (8). The distributor (8) is arranged between guides (13 and 14) and has a pressure aperture (15) and an intake aperture (16). An aperture (17) for the admission of operating fluid to the cylinder block and an aperture (18) for the discharge of working fluid are made in the cover. The intake aperture (16) of the distributor (8) is connected to the internal chamber of the housing via ducts (19 and 20), which run outwards to the surfaces (21 and 22) of the distributor and are fixed in this in its direction of displacement on both sides of a plane which is perpendicular to this direction of displacement. <IMAGE>

Description

DESCRIPTION

The invention relates. * To hydraulic drives, in particular on hydraulic machines with adjustable volume, and can be used in machines for various purposes, which have a hydraulic drive, for example in Dredging can be applied.

Are known hydraulic axial piston variable displacement pumps that contain a housing, in the interior of which a drive shaft is housed with a "square to her." arranged rotating cylinder block is connected, wel-

themselves
rather / is supported against the housing cover via a movable distributor, the suction and pressure openings of which are connected to corresponding openings in the housing cover (see Uü- Patent No. 2967491, EL. 103-162, 1961-, UdäüS-üiheb see in No. 568737, class B ¹ 04 B 1/12, 1977). The suction opening of these pumps is isolated from the interior of the housing, which is why the working fluid only enters the cylinder block from a working fluid container when it is sucked in. Yes, the supply line creates a resistance to the movement of the working fluid in it, so at high speed of the cylinder block an incomplete precipitation of its cavities and a separation of gases dissolved in the fluid can take place, which leads to a pressure pulsation of the working fluid in the hydraulic- Pressure line of the pump leads. These circumstances "limit the speed of the cylinder block and worsen the cavitation behavior of the pump.

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Hydraulic pumps with an immovable distributor are known which have two suction openings, each cavity of the cylinder block having two bores of different diameters, which are attached at different distances from the cylinder block axis (see DS application no. 221 ^ 400 »cl. 59a 14, 1972). When the cylinder block rotates, the smaller-diameter bore is connected to the interior of the housing via one of the suction openings and the channels in the distributor, while the larger-diameter bore is connected to the other suction opening (main opening). During the work of such a pump, the working fluid enters the cylinder block not only from the container _j but also from the interior of the housing, where it collects as a result of leaks through the clearances between the individual parts of the pump, which improves the filling of the cavities of the cylinder block and the Pressure pulsation of the working fluid in the hydraulic pressure line is reduced »With this design, however, the construction of the pump becomes more complicated, the diameter of the adjacent surfaces of the cylinder block and the distributor increases and as a result the sliding speeds, the wear and the leakage flow of the working fluid (via the additional holes of smaller diameter during the compression of the liquid in the cavity of the cylinder block),

Ss are hydraulic variable displacement pumps with a movable distributor known, in which the suction opening is missing (see US-PS No. 4198899, class 91-505, 19Ö0; üJS application Hr.2642900, class.

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J? - 04 B 1/24, 1976). The suction of the working fluid into the cavities of the cylinder block takes place in these pumps directly from the housing. However deteriorated for a selbstansäugende pump such an embodiment & ugcedindungen the Ans (the dtrom the Arbeitsflussigkeit from entering the cylinder block because of the Hi entVorhandenseins the suction opening nicnt formed and the action of transversely directed to the current centrifugal forces generated by the rotating cylinder block, exposed ).

Hydraulic axial piston variable displacement pumps with a movable distributor in which the length of the opening in the housing cover is known are known for the supply of the working fluid is so much greater than the length of the distributor that in all positions of the distributor in relation to the cover during the adjustment, the suction opening communicates with the cavity of the housing (see accepted DE application Mr. 24015J1, class 04 B 1/24, 1975). This results in the discharge of the working fluid out of the housing and the filling of the cavities of the cylinder block improves in the period where it is the distributor when adjusting at a low speed shifts or the adjustment is not made and the distributor comes to a standstill.

During the rapid displacement of the distributor together with the cylinder block during the adjustment however, the resistance of the working fluid located in the interior of the housing to this displacement increases, which reduces the quick action when adjusting (especially with high viscosity of the working fluid). The pressure of

Liquid rises in front of the distributor and sinks behind it. v. ^: Egen the resulting negative pressure reduces the volume of from the region of the housing interior and generous extracted Aumes behind the distributors working fluid, nevertheless in this area, the surface area of the released during the displacement of the distributor opening for Ärbeitsflüssigkeitszuführung increases. At the same time, the volume of the liquid that is sucked out of the area in front of the distributor, in which the pressure increases, but the surface area of the opening, which is closed when the distributor is moved, decreases and the resistance to the supply of the working fluid in The opening of the distributor from the inside of the housing becomes larger (an increase in the length of the opening would reduce the strength of the cover, which is bent by the pulsating load on the part of the distributor), in connection with this the filling of the Cavities in the cylinder block, which only lasts for a short time (during adjustment), but at high cylinder block speed it can lead to an increase in the pressure pulsation of the working fluid in the hydraulic pressure line or to cavitation and a reduction in the service life of the hydraulic pump. The named causes limit the speed of the cylinder block (high speed) and / or the displacement speed of the distributor (rapid action of the hydraulic pump during regulation, its flow rate).

The purpose of the invention is to remedy the aforementioned Disadvantage.

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The object of the present invention is to create such a hydraulic axial piston variable displacement pump in which, in the state of üelbstansaugens, the flow resistance to the supply of working fluid from the interior of the housing into the suction opening of the distributor depends on its position in relation to the housing cover when regulating the Troy conveying the hydraulic pump and of the Verschiebungsgeschwindi _t, ness does not depend of the manifold.

The problem posed is achieved in that in the hydraulic axial piston variable displacement pump, which contains a housing, in the interior of which a drive shaft is housed which is connected to a circumferential cylinder block arranged on it at an angle, which is opposite the housing cover is supported by a movable distributor with a suction opening, which with the housing interior and with an opening provided in the housing cover for the supply of the working fluid to the cylinder block stands, according to the invention, the suction opening of the distributor with the interior of the housing is in communication by means of channels, which are in the distributor in the direction of displacement of the same on both sides are attached with respect to a plane which is perpendicular to this direction of displacement.

The proposed invention allows the fast running igke it in operation of the hydraulic pump in the state the self-priming and the quick action when adjusting to increase.

This is ensured by the fact that the flow resistance

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state of the channels in the "distributor which the working fluid from eggs .... zone of the housing chamber, before; itself, moving distributor (from the zone erhöhten.Drucks) in which u ansoffηung out from the Lace thereof with respect to egg s . ge ha use- lid and the Versciiiebungs ^ eschwindigkeit the distributor during the adjustment does not depend on this at the same time, the pressure difference of the working fluid before and lowered xiinter the shifting distribution, suggesting the overcurrent · _-;.. inung the liquid over the in distribution u-jaoenen front channels from the zone of increased pressure of the working liquid is in the zone of decreased pressure due (hinter.dem distributor) Thanks to this fact .nimmt, DER the Arbeitsflüssi resistant ^ ness in increasing the _{Verscniebungsge-;.} sohwindi _r ility of the distributor decreases during the adjustment and the process of filling the cavities of the cylinder block is improved, which increases the pressure pulsation of the working fluid in the JSr increasing the speed and reducing the probability of the occurrence of cavitation, as well as: thereby eliminating the above-mentioned disadvantages of the known hydraulic pump.

Other objects and advantages of the present invention become from the following detailed description of a

Exemplary embodiment of the pump and from the attached Drawings understandable ", ■ it shows

.fig.l a longitudinal section of the hydraulic pump;

Figo 2 shows a cross section of the distributor and the one on it adjacent components of the hydraulic pump; Fig. 3 schematic arrangement of the distributor between

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31TS994 - ε -

Guides.

The hydraulic pump shown in Fig * 1-3 contains a housing 1, in whose jjuienraum 2 a drive shaft 3 is housed, which has a disc 4, connecting rods !? and Lolben b ait one under a V / angle to the drive shaft 3 arranged cylinder block 7 is in connection, wel- ' cner itself against the lid via a movable distributor 8 9 of the housing 1 is supported. In the middle of the distributor 8 is a bore IO is present, into which the bolt 11 of a power piston 12 protrudes. The distributor 8 is between fixed guides 13 and 14, which extend to the longitudinal axis of the power piston 12 run parallel, arranged and has on one side in with respect to this axis a back opening 15 and "on the other Open an eye opening 16. They are adjacent to one another Surfaces of the distributor δ and the cover 9 are curvilinear (cylindrical or spherical) »In the cover 9 there is an opening 17 for the supply of a working fluid from a working fluid container to the cylinder block and an opening IS for the discharge of the working fluid underneath There is pressure in the hydraulic pressure line of the pump. The length of the openings 17 and 18 must be sufficient to Cover with the corresponding openings 16 and 15 of the Distributor 8 in any position of the same at his Displacement on the cover 9 during the adjustment. The opening 17 can be connected to the interior space 2 of the housing 1 stand, including the length of the opening 17 greater than the length of the distributor must be β, it can also be from this Irinenraum 2 be separated during adjustment. The suction opening 16

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of the distributor ö stands with de; - * lnnenraura. 2 of the housing 1 by means of channels V-) and 20 in connection, which go out onto the outer surfaces 21,22 of the distributor b and are attached in displacement sr i ent ung the same on both sides with respect to a plane which is perpendicular to this direction of displacement.

During the work of the hydraulic pump, the connecting rods 5, the pistons 6 and the inclined cylinder block 7 rotate together with the -.Velie, 3 and the cicneioe 4, whereby trees of variable volume arise between the latter and the pistons 6. The maximum size of the cavity volume depends on the stroke of the piston 6 and the angle of inclination of the cylinder block 7 with respect to the axis of the l ^ elle 3. This angle is adjusted by moving the distributor ο by means of the bolt 11 along the guides 13 and 14 relative to the kruranilinigen surface of the cover 9, around the center of which the distributor b rotates together with the cylinder block y.

Most of the working fluid flows into the cavities of the cylinder block rotating relative to the distributor ö 7 from the working fluid container through the opening 17 in the Lid 9 and the suction opening 16 of the distributor 6. The workflow igke it comes under pressure from the cavity of the cylinder block 7 as it continues to rotate and through the Piston 6 performed compression ^ the liquid in the Pressure opening 15 of the distributor ö and then into the opening lö im .Cover 9 for discharging the working fluid into the hydraulic Pressure line of the pump. The in the cavities of the cy-

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Linderblocks' / compressed working fluid penetrates through the clearances between the components into the interior. 2 of the housing 1. As a result of a pressure difference, the working fluid comes out of this interior space. 2 via the channels 19 and 20 of the distributor 8 , which is stationary or moving at a low speed, into its suction opening 16 and is then sucked into the cavities of the cylinder block 7 together with the working fluid arriving via the opening 1 '/ in the cover 9, whereby it the filling of the latter is improved.

If the distributor ö and the -i / lind block 7 are shifted quickly during the adjustment, the i / cuck increases. the working fluid in the zone of the interior space 2 in front of the distributor 8 (for example between its outer surface 21 and the walls of the housing 1) and sinks in the zone behind the distributor ü (between its outer surface 22 and the walls of the housing 1). The channels 19 and 20 connect these zones with each other, and the working fluid flows over these channels 19 »20 from the zone of the interior space 2 of increased pressure into the zone of reduced pressure by the pressure difference in these zones and the resistance of the working fluid to the displacement of the distributor 8 is reduced. This increases the quick action of the hydraulic pump during adjustment. Since the working fluid then passes through the suction opening 16 of the distributor 8, the connection of this opening 16 with the zone of the interior 2 of increased pressure via the channel 19 also improves the filling of the cavities of the cylinder block (the

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Excess of the working fluid that enters the cavities of the Manifold 8 has not reached, flows through the channel 20 in the zone of the interior 2 reduced pressure above and reduced the .pressure difference in these zones * as above mentioned). By the fact that the surfaces of the Channels 19 and 20 as well as their otröuiun ^ resistance. of the location of the distributor 8 with respect to the cover 9 during the adjustment do not depend, the increase in the speed of displacement improves of the distributor B the process of filling of the cavities of the cylinder block 7 · U the length of the opening in the cover 17 can be reduced, which the bending stiffness des -ueckels 9 increased. .Jie channels 19 and 20 are in the least polluted part of the "distributor", why their presence ία distributor a no significant i / influis on its strength.

Thus, the presence of the above-described channels 19 and 20 in the distributor 8 improves the precipitation of the cavities of the cylinder block 7 »eliminates the causes which lead to the occurrence of cavitation and to the intensification of the pulsation of the working fluid. This offers the possibility of increasing the speed of the cylinder block 7 (speed of the hydraulic pump) and of increasing the displacement speed of the distributor 8 and thus the rapid action of the hydraulic pump in regulating its flow rate.

Claims (1)

HYDRAULIC AXIAL PISTON VEFISTS S PATEHTANSPHÜCH Hydraulic variable displacement axial piston pump that has a housing contains j in the interior of which a drive shaft is housed, which is arranged with a '»' / angled to it rotating cylinder block is connected, which is against the housing cover via a movable distributor with a The suction opening is supported with the interior of the housing and with an opening provided in the housing cover for the feed the working fluid is in communication with the cylinder block, characterized in that the sucking opening of the distributor / Ö / with the interior / 2 / of the housing / 1 / by means of channels / 19 / and / 20 / in connection, which in the distributor / 8 / in the direction of displacement of the same on both sides with respect to an iibene are attached, which to this Direction of displacement is perpendicular «,