EP1944510A1 - Piston type machine having a tiltable cylinder sleeve - Google Patents

Abstract

Piston engine comprises a spring element (116) which pivots corresponding to the movement of a cylinder sleeve (36, 38). Preferred Features: The spring element interacts with the first end section (122) on an inner peripheral groove (124) of a cylinder sleeve and with a second end section (126) on a cylinder drum (32, 34). The spring element is formed as a sheet metal bent part.

Description

piston engine

The invention relates to a piston engine according to the preamble of patent claim 1.

Such, designed as an axial piston piston machine is, for example, from the post-published DE 10 2005 056 631.6 known. This conventional solution has two approximately in the axial direction oppositely directed rows of pistons, which are in operative connection with one of a swash plate frontally supported cylinder drum, which has a plurality of pivotally mounted and supported on an end face of a drum base of the cylinder barrel cylinder sleeves. The rows of pistons each consist of a plurality of pistons, which are each received in a cylindrical sleeve of the cylinder drums relative to axially displaceable and connected to a shaft which acts as a drive or output shaft depending on the design of the axial piston machine. Due to the inclination of the cylinder drums, the rotation of the pistons about the shaft axis and a corresponding pivoting or wobbling movement of the cylinder drums results in a transverse movement between the pistons and the cylinder drums, made possible by the end faces of the drum base being provided with spherical protrusions as bearing seat elements are, on each of which one of the cylinder sleeves is supported on the foot side, so that the cylinder sleeves are pivotally mounted with respect to the swash plate. In order to ensure a sufficient sealing effect between the cylinder sleeves and the drum base, the cylinder sleeves are biased by spring elements, which act against the sealing points opposite flat surfaces of the cylinder sleeves, sealingly against the spherical projections of the drum base.

A disadvantage of such reciprocating engines is that between the cylinder sleeves and acting on the flat surfaces of the cylinder sleeves spring elements, a sliding movement can occur, causing friction losses and affects the pivoting or tumbling motion of the cylinder sleeves. A further disadvantage is that a tilting moment can occur which leads to tilting of the cylinder sleeves from the bearing seat elements and thereby to a pressure medium leakage and to a deteriorated volumetric efficiency of the piston engine. It has also been shown that in such solutions no constant contact pressure can be achieved.

In contrast, the present invention seeks to provide a piston engine, in which with minimal manufacturing effort a constant mechanical contact / bias of the cylinder sleeves is achieved against the crowned bearing seat elements without hindering the pivoting or tumbling motion of the cylinder sleeves.

This object is achieved by a piston engine having the features of patent claim 1.

The piston engine according to the invention has at least one pivotally mounted cylinder sleeve, in which a piston is immersed, which is operatively connected to a drive / output shaft, wherein the cylinder sleeve is biased by at least one spring element against a bearing seat member. According to the invention, the spring element is pivotable in accordance with the movement of the cylinder sleeve. This solution has the advantage that the pivoting or wobbling movement of the cylinder sleeves by the spring elements (hold-down springs) is not affected, since the spring elements over the prior art according to the DE 10 2005 056 631.6 are pivotable, so that a sliding movement between the cylinder sleeves and the spring elements and a tilting moment of the cylinder sleeves is avoided on the bearing seat elements or at least greatly reduced. Furthermore, due to the pivotable spring elements a centric, substantially constant contact force the cylinder sleeves against the bearing seat member and thus achieves a high sealing effect at static spring load and significantly reduced friction.

It has proved to be particularly advantageous if the spring element engages with a section which dips into the cylinder sleeve. As a result, the introduction of force of the spring element and thus the sealing effect and Abkippsicherheit is further improved.

According to a particularly preferred embodiment of the invention, this is designed as an axial piston machine with at least one swash plate, on each of which a cylinder drum is supported, which has a plurality of pivotally mounted on an articulated or spherical projections end face of a drum base of the cylinder drum supported cylindrical sleeves in which piston are guided, which are operatively connected to a drive / output shaft, wherein the cylinder sleeves are biased by at least one spring element against a respective hinge element, such as a ball screw, or a convex projection of the drum base.

Preferably, the spring element engages with a first end portion of an inner circumferential groove of the cylinder sleeve and is supported with a second end portion of the cylinder barrel, so that the cylinder sleeves are biased against a respective hinge element or a convex projection of the drum base. Here, it is preferred if the spring element engages via spring legs in the inner circumferential groove of the cylinder sleeve.

In a preferred variant of the invention, the spring legs each have an axial section extending approximately in the axial direction, which merges into a radial section bent outwards and back to the inner circumferential groove. For example, the spring element has three or five spring legs, which are arranged approximately crown-shaped and engage in the inner circumferential groove. Due to the three or five spring legs is a statically certain support of the cylinder sleeve on the hinge element or the projection of the drum base and thereby achieved a high Abkippsicherheit with minimal manufacturing effort. Such a spring element can be particularly advantageous in terms of production as a sheet metal bent part.

It has proven to be particularly advantageous if the second end portion of the spring element for articulated mounting of the spring element is at least partially spherical, so that the spring element with the cylinder sleeve is pivotable.

In an alternative embodiment of the invention an engaging on the cylinder sleeve end portion of the spring element is connected via a flexible tensile element, preferably a wire, with an attacking on the cylinder drum end portion. In this variant, the pivoting movement of the upper part is made possible by the flexurally soft tension element. The lower part of the spring element may be stationary or articulated relative to the drum base or the ball head in this solution.

It has proved to be particularly advantageous if the flexurally soft tensioning element extends substantially along the longitudinal axis of the spring element. As a result, a centric contact force of the cylinder sleeves against the bearing seat element and thus a high sealing effect is achieved.

In one embodiment of the invention with joint element, the spring element preferably extends into the joint element and is connected via this with the cylinder drum. For example, a ball screw is used, which is screwed into a receptacle of the cylinder drum, wherein an end portion of the spring element between the ball screw and the cylinder drum axially fixed but is pivotally mounted.

According to an alternative variant of the piston engine, the cylinder sleeves are each prestressed against the bearing seat element by means of at least one tension spring, for example a helical spring.

In one embodiment of the invention, the spring element passes through the cylinder drum at least in sections and is connected to the rear side with this.

It is preferred if the spring element engages in the region of a sealing portion on the cylinder sleeve, so that any tilting moment that may occur is further reduced and tilting of the cylinder sleeves from the bearing seat elements is prevented.

In one embodiment of the piston engine, the spring element is arranged in the cylinder sleeve such that the cylinder sleeve and the spring element extend substantially along a common longitudinal axis.

In a preferred embodiment, the hinge elements or the convex projections dip into the cylinder sleeves in sections. It is advantageous if the cylinder sleeves are spaced from an end face of the drum base, so that the cylinder sleeves do not accumulate on a pivoting movement on this surface. In the same level with the drum level plane lying sealing level, the distance can also be achieved by an annular groove (concentric with the sleeve / Kugelkopfachse) in the drum disc.

Preferably, the spherical projections bound with their surfaces at least partially cylinder chambers of the cylinder sleeves. To produce a pressure medium connection between the cylinder chambers and a suction or pressure connection of the axial piston machine, the joint elements or the convex projections each have a bore open towards the cylinder space, which opens into an opening of the drum base, which can be brought into coincidence with controlling the swash plates , Here is it is particularly advantageous if the spring elements form a flow cross-section.

Other advantageous developments of the invention are the subject of further subclaims.

• Figur 1 einen Längsschnitt durch eine als Axialkolbenmaschine ausgebildete erfindungsgemäße Kolbenmaschine gemäß eines ersten erfindungsgemäßen Ausführungsbeispiels;
• Figur 2 eine Detaildarstellung der Axialkolbenmaschine aus Figur 1 und
• Figur 3 eine Detaildarstellung einer Axialkolbenmaschine gemäß eines weiteren erfindungsgemäßen Ausführungsbeispiels.

In the following preferred embodiments of the invention will be explained in more detail with reference to schematic drawings. Show it:

• FIG. 1 a longitudinal section through a designed as an axial piston piston engine according to the invention according to a first embodiment of the invention;
• FIG. 2 a detailed view of the axial piston from FIG. 1 and
• FIG. 3 a detailed view of an axial piston machine according to another embodiment of the invention.

FIG. 1 shows a longitudinal section through a designed as an axial piston piston engine according to the invention 1, which can be operated both as a hydraulic motor and as a pump. The axial piston machine 1 has a housing 2 indicated by dashed lines, on which a suction port, not shown, and a pressure port (not shown) are formed. The housing 2 is designed in several parts and has two covers 4, 6, between which a sleeve-shaped middle part 8 is clamped to limit an interior 10. The interior 10 is penetrated by a drive shaft 12 which is mounted in the housing 2 via a roller bearing 14, which is inserted into an inner bore 16 of the lid 4, and by a roller bearing 18 which is arranged in an inner bore 20 of the lid 6 , A protruding from the housing 2 free end portion 22 of the drive shaft 12 is connectable to a drive motor, not shown. In the interior 10 are rotatably on the lids 4, 6 or adjustable in inclination two swash plates 24, 26, each with an obliquely to the shaft axis W of the drive shaft 12 extending support surface 28, 30 are arranged. On each of these is mounted on the drive shaft 12 cylinder drum 32, 34 supported, which has a plurality of cylinder sleeves 36, 38, in each of which a piston 40, 42 of a piston row 44, 46 is immersed. The cylinder drums 32, 34 are pivotally mounted on the drive shaft 12, so that due to their inclination during a rotation of the drive shaft 12, a wobbling motion is effected. In this case, the cylinder drums 32, 34 are each driven by two engaging on a casing part 48, 50 of the cylinder drums 32, 34 driving pins 52 in the direction of rotation, each in a ball bearing portion 54, 56 of the drive shaft 12 passing through transverse bore 58, 60 are inserted in sections. The cylinder drums 32, 34 are each supported by a drum bottom 62, 64 on the respective support surface 28, 30, wherein they by means of a tension spring 66, 68, between each one on the bearing portion 54, 56 pivotable support ring 70, 72 and a in an inner peripheral groove 74, 76 of the drum base 62, 64 received circlip 78, 80 extends, are biased against the respective support surface 28, 30. The swash plates 24, 26 are symmetrical to in FIG. 1 arranged vertically extending center plane M, wherein the support surfaces 28, 30 are each inclined to the center plane M. The pistons 42 have a substantially conical shape and form with the piston 40 respectively end portions of a double piston 82 facing away from each other, which is screwed with a central portion 84 in a threaded bore 86 of a radially projecting drive flange 88 of the drive shaft 12. The depth of engagement of the central portion 84 is limited by a radial shoulder 90 of the double piston 82, which rests in the end position with a shoulder surface 92 frontally on the drive flange 88. Further details of the axial piston machine 1 are based on the detailed representation of the cylinder drum 34 in FIG. 2 explained.

According to FIG. 2 each of the pistons 42 is spaced from the central portion 84 (see FIG FIG. 1 ) extending shank 94, which with a conical piston head 96 in a cylinder bore 98 of the cylinder sleeves 38th dips and sealingly abuts a peripheral wall 100 of the cylinder sleeves 38 and a cylinder space 102 limited. In the piston head 96, a kelchartiger, to the cylinder chamber 102 toward the open piston chamber 104 is each frontally formed, which merges into a provided with an internal thread 106 blind bore 108 and allows the piston head 96 can be acted upon in a compression stroke with high pressure, so that it geometrically to which can be adapted radially expanding cylinder sleeve 38 during a compression stroke of the piston 42 and thus sealingly abuts the peripheral wall 100 of the cylinder sleeves 38 in each working position. To reduce the compression volume formed by the cylinder chamber 102 and the piston chamber 104 and to reduce the dead volume, an insert 110 can be inserted into the piston chamber 104, which is secured by a screw 112 passing through it and being in operative engagement with the internal thread 106. The insert 110 has a gap so that the piston head 96 can radially expand during a compression stroke to prevent leakage. The cylinder sleeves 38 are biased via a sealing portion 114 by means of a spring element 116 against each one, as in a stepped bore 118 of the cylinder barrel 34 screwed ball screw 120 formed bearing seat member of the drum base 64. In a variant of the invention, not shown, the cylinder sleeves 38 are biased against a convex projection of the drum bottom 64. The spring element 116 engages with a dipping into the cylinder sleeve portion 122 at this 122 and is pivotally mounted according to the movement of the cylinder sleeve 38. As a result, the pivoting or tumbling motion of the cylinder sleeves 38 is substantially unaffected by the spring elements 116, so that a sliding movement between the cylinder sleeves 38 and the spring elements 116 and a tilting moment of the cylinder sleeves 38 on the ball screws 120 avoided or at least greatly reduced. Due to the pivotally mounted spring elements 116 a centric, substantially constant contact force of the cylinder sleeves 38 against the ball screws 120 and thus a high sealing effect at substantially reduced friction is further achieved. Furthermore, the spring elements 116 are loaded only statically, since these according to the sleeve movement a pivoting movement To run. The spring element 116 engages in the illustrated embodiment with the first end portion 122 at an inner circumferential groove 124 of the cylinder sleeve 38 and is attached via a second end portion 126 to the cylinder barrel 34, so that the cylinder sleeve 38 is biased against the ball screw 120. For this purpose, the spring element 116 engages via spring legs 128 in the inner circumferential groove 124 of the cylinder sleeve 38 having an axially extending axial portion 130 which extends at a distance through a through hole 131 of the ball screw 120 and into a bent outwardly and back to the inner circumferential groove 124 radial portion 132nd passes. In the illustrated embodiment, the spring element 116 has five spring legs 128, which are approximately crown-shaped and engage in the inner circumferential groove 124. Due to the five spring legs 128, a statically determined support of the cylinder sleeve 38 and thereby a high Abkippsicherheit achieved with minimal manufacturing effort. The inner circumferential groove 124 is formed in the region of the sealing portion 114 of the cylinder sleeve 38, so that a possibly occurring tilting moment is further reduced and tilting of the cylinder sleeves 38 is prevented. The spring element 116 extends through the ball screw 120 into a space 134 and is connected via this to the drum base 64, wherein the end portion 126 of the spring element 116 to its articulated mounting partially spherical with spherical segments 136 and between a corresponding recess 138 of the ball screw 120th and the drum base 64 is arranged positively but pivotally. The spring element 116 is arranged in the cylinder sleeve 38 such that the cylinder sleeve 38 and the spring element 116 substantially extend along a common longitudinal axis 140. Such a spring element 116 is particularly advantageous in one piece as sheet metal part produced.

According to a variant of the invention, not shown, the cylinder sleeves 38 are each biased by means of at least one tension spring, such as a coil spring, against the ball screw.

In FIG. 3 is a detailed illustration of an axial piston machine 1 according to another embodiment of the invention shown that differs from the above-described embodiment essentially in that the engaging on the cylinder sleeve 38 end portion 122 of the spring element 116 via a flexurally soft tension member 146 with the cylinder drum 34 and the Bearing seat member 120 engaging end portion 126 is connected. The bending-soft tension element 146 is formed in the illustrated embodiment as a wire, which engages over a respective transverse strut 148, 150 on a cylinder sleeve 152 of the upper part 122 or the ball segments 136 of the lower part 126 and the pivoting movement of the upper part 122 allows. The cylinder sleeve 152 and the ball segments 136 allow a sufficiently large flow cross-section of the spring element 116. It has proven to be particularly advantageous if the flexurally soft tension element 146 extends along the longitudinal axis 140 of the spring element 116. As a result, a centric contact force of the cylinder sleeves 38 against the bearing seat element 120 and thus a high sealing effect is achieved. The lower part 126 of the spring element 116 is according to FIG. 3 articulated relative to the cylinder drum 34. Since in this variant, a pivoting movement of the upper part 122 is made possible by the flexurally soft tensioning element 146, the lower part 126 in an embodiment, not shown, of the spring element 116, however, also be stationary relative to the cylindrical drum 34.

To produce a pressure medium connection between the cylinder chambers 102 and a suction or pressure connection of the axial piston machine 1, the ball screws 120 are respectively penetrated by the cylinder chamber 102 to open hole 118, which opens into an opening 142 of the drum bottom 64, so that, as shown , the bore 118 is extended through the drum bottom 64 and can be brought into overlap with unillustrated control kidneys of the swash plate 26, so that in dependence on the rotational position (inner, outer dead center) of the cylinder drum 34 made a connection with the suction or the pressure port is to nachzusaugen pressure medium in the cylinder chamber 102 or with High pressure pressurized fluid to lead to a consumer. Here, the spring elements 116 form a flow cross-section. The cylinder sleeves 38 are at the foot side spaced from an end face 144 of the drum base 64, so that the cylinder sleeves 38 do not accumulate on a transverse movement and are lifted from the ball screws 120.

Disclosed is a piston engine 1 with at least one pivotally mounted cylinder sleeve 36, 38 in which a piston 40, 42 is immersed, which is operatively connected to a drive / output shaft 12, wherein the cylinder sleeve 36, 38 by means of at least one spring element 116 against a bearing seat member 120 is biased. According to the invention, the spring element 116 is pivotable in accordance with the movement of the cylinder sleeve 36, 38.

Claims (19)

Piston machine with at least one pivotally mounted cylinder sleeve (36, 38) into which a piston (40, 42) immersed, which is in operative connection with a drive / output shaft (12), wherein the cylinder sleeve (36, 38) by means of at least one spring element (116) is biased against a bearing seat member (120), characterized in that the spring element (116) in accordance with the movement of the cylinder sleeve (36, 38) is pivotable. Piston engine according to claim 1, wherein the spring element (116) with a in the cylinder sleeve (36, 38) dipping portion (122) engages thereto. Piston engine according to claim 1 or 2, comprising at least one swashplate (24, 26) on which is supported a cylinder drum (32, 34) which has a plurality of end faces (144, 84) pivotally mounted on a joint element (120) as bearing seat elements or crowned protrusions ) a drum base (62, 64) of the cylinder drum (32, 34) supported cylindrical sleeves (36, 38), in which the pistons (40, 42) are guided, which are in operative connection with the input / output shaft (12), wherein the cylinder sleeves (36, 38) by means of at least one spring element (116) against each a hinge element (120) or a convex projection of the drum base (62, 64) are biased. The piston engine of claim 3, wherein the spring member (116) engages the first end portion (122) on an inner circumferential groove (124) of the cylinder sleeve (36, 38) and a second end portion (126) on the cylindrical drum (32, 34). Piston engine according to claim 4, wherein the spring element (116) via spring legs (128) engages in the inner circumferential groove (124) of the cylinder sleeve (36, 38). A piston engine according to claim 5, wherein the spring legs (128) each have an approximately axially extending axial portion (130) which merges into a radially outwardly and backwardly to the inner circumferential groove (124) curved radial portion (132). Piston engine according to one of the preceding claims, wherein an on the cylinder sleeve (36, 38) engaging end portion (122) of the spring element (116) via a flexible tensile element (146), preferably a wire, with a on the cylinder drum (32, 34) engaging End portion (126) is connected. A piston engine according to claim 7, wherein said flexurally soft tension member (146) extends substantially along the longitudinal axis (140) of said spring member (116). Piston engine according to one of claims 3 to 8, wherein the second end portion (126) of the spring element (116) is at least partially spherical. Piston engine according to one of the preceding claims, wherein the spring element (116) is designed as a sheet metal bent part. Piston engine according to one of claims 1 to 5, wherein the cylinder sleeve (36, 38) by means of at least one tension spring, preferably a coil spring, is biased against the bearing seat member (120). A piston engine according to any one of claims 3 to 11, wherein the spring member (116) extends through the hinge member (120) and is connected therewith to the cylinder barrel (32, 34). Piston engine according to one of claims 3 to 11, wherein the spring element (116) passes through the cylinder drum (32, 34) at least in sections and is connected to the rear side thereof. Piston engine according to one of the preceding claims, wherein the spring element (116) engages in the region of a sealing portion (114) on the cylinder sleeve (36, 38). Piston engine according to one of the preceding claims, wherein the cylinder sleeve (36, 38) and the spring element (116) extend substantially along a common longitudinal axis (140). Piston engine according to one of the preceding claims, wherein the spring element (116) forms a flow cross-section. A piston engine according to any one of claims 3 to 16, wherein the cylinder sleeves (36, 38) are spaced from an end face (144) of the drum bottom (62, 64). Piston engine according to one of claims 3 to 17, wherein the hinge elements (120) or spherical protrusions submerged in sections in the cylinder sleeve (36, 38) and cylinder spaces (102) of the cylinder sleeves (36, 38) limit. Piston engine according to one of claims 3 to 18, wherein the joint elements (120) or spherical projections each have a cylinder space (102) open bore (118) which opens into an opening (142) of the drum base (62, 64), which can be brought into overlap with the control of the swash plate (24, 26).

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