EP1050680A2 - Shaft seal for hydraulic machine - Google Patents

Abstract

The machine has a housing (2) in which a rotatable drive shaft (5) fits through a wall (2a) hole (8). A roller bearing (7) i located on the housing wall, on which an external primary sealing component (9) is fitted. In the space between the primary seal component and the roller bearing a second sealing component (26) is fitted, which divides the space into an inner area (3a) accommodating the roller bearing and intermediate space (27) between the primary and secondary sealing components. The intermedi space is connected with a drainage conduit (31), in which a pressure appertains, which is lower than that in the inner area (3a)

Description

The invention relates to a hydraulic machine according to the preamble of claim 1.

This is a common construction method a hydraulic machine that is in practice has enforced and z. B. described in DE 196 13 609 A1 is. For the one that can be found in this publication hydraulic machine is a Axial piston machine with a drive shaft, which by means of a Rolling bearing on a housing wall of the housing stored hydraulic machine and by means of a outside of the rolling bearing in an annular joint between the Drive shaft and the housing wall arranged sealing ring is sealed. In this known hydraulic machine is also a pump device for an internal Forced flushing of the roller bearing is provided. The Pump device has one on the inside of the Roller arranged on the conveyor disc, the annular gap of the rolling bearing axially opposite through holes has, which with respect to the axis of rotation of the shaft in Extend divergent direction towards the rolling bearing. Hereby acts on the conveyor disc, which functions during operation at least partially in the hydraulic operating fluid, e.g. B. Hydraulic oil, like a centrifugal pump, is located that in the diverging through holes located fluid due to the centrifugal force in the direction of promotes the rolling bearing. On the side facing away from the conveyor disc A return channel is provided on the side of the roller bearing, which extends back into the interior of the housing and in which the delivered fluid flows back into the interior can.

In this known axial piston machine, the Flow of forced flushing from the outer annular gap of the Rolling through radially outwardly directed channels from an annulus approximately radially outwards, the funded Flushing fluid flows across the annulus.

In this known embodiment, the first Sealing element lubricated by the flushing fluid and cooled, but there is also pressure fluctuations in the interior exposed to the machine housing, the Pressure fluctuations are essentially caused by the rolling bearing propagate undiminished to the first sealing element. As a result, a pressure difference acts on the first sealing element, which is due to the inside of the first sealing element pending internal pressure and the housing surrounding air pressure results. If this pressure difference is one exceeds a certain permissible value is a Desirably good sealing function of the first sealing element no longer exist. The sealing function can be performed by a sudden overuse or persistent Overuse can be affected. The latter are especially with such first sealing elements, the drive shaft of the machine with a sealing lip surrounded with increasing internal pressure against the Shell surface of the drive shaft is pressed. Unless already because of the high pressure in the interior basically impairments of the first sealing element arise, there is a risk of increased frictional wear on the sealing lip.

Another problem, both in combination and is independent of the problem described above to see that there is some leakage at the first Sealing element can hardly be avoided. This leak occurs due to the relative movement between the first Sealing element or its sealing lip and the drive shaft, taking it especially at pressure peaks and out of it resulting pressure fluctuations in the relative movement, between the first sealing element or its sealing lip and the drive shaft takes place, to an increased leakage on comes first sealing element or on the sealing lip.

The invention has for its object in a hydraulic machine of the type specified at the outset Improve sealing of the drive shaft.

This object is achieved by the features of claim 1 solved.

Advantageous developments of the invention are in the Subclaims described.

In the machine according to the invention there is between the first sealing element and the rolling bearing extending space a second sealing element is arranged, the space in one the rolling bearing receiving interior and one between the first sealing element and the second sealing element arranged space separates, the space with a drainage line is connected, in which a pressure prevails, which is lower than the pressure in the interior. The second sealing element thus forms a barrier that in is beneficial in two ways.

On the one hand, it forms a barrier against pressure fluctuations, in particular sudden pressure increases such as pressure peaks, in Main room so that this is not in the adjoining room reproduce and increasingly use the sealing ring or can overuse. This is especially true for one such a sealing ring, which extends axially inwards has annular sealing lip, which in the event of a pressure increase is pressed against the drive shaft, the Surface pressure between the sealing lip and the drive shaft significantly enlarged and increased wear the sealing lip leads.

On the other hand, the partition wall forms a barrier against the hydraulic fluid contained in the main room Solid contamination, especially from abrasion resulting particles, thus neither in the adjoining room can still reach the sealing surface on the sealing ring can affect. Advantageous further developments of Invention are described in the subclaims.

Since the second sealing element withstands the pressure fluctuations of the Interior is still exposed, is with a Leakage at the second sealing element can be expected, however this leakage does not affect the environment of the hydraulic Machine, because it is separated from the space by a Drainage line discharged. Since in the invention Design the first sealing element of the Pressure fluctuations or from increased pressures is exempt or the pressure fluctuations are reduced, a Leakage at the first sealing element avoided, so that the hydraulic machine is of clean function and also on Can be placed in locations where the avoidance of Leakage is required.

In addition, the invention is distinguished Design through a simple and inexpensive manufacturable construction, which is also of small size and therefore with all common machine types can be realized.

The configuration according to the invention comprises a pressure stage seal with a second sealing element that from the hydraulic fluid on the inside of it with a small amount of fluid is passed. With this amount of fluid it is a leakage amount or one Amount of fluid that bypasses the second sealing element happens.

Several are suitable as the second sealing element Configurations. It can e.g. B. a radial shaft seal, a mechanical seal or a gap or Act labyrinth seal. The the second sealing element passing amount of fluid is expelled through the drainage line drained the space, which on the one hand Lubrication of the first sealing element is guaranteed and on the other hand that which passes through the second sealing element Fluid causes no pressure increase in the space.

Features are contained in the subclaims which Sealing continues to improve, the lubrication of the first Improve sealing element, and also advantageous features for draining the intermediate leakage on the second sealing element and for lubricant supply.

Fig. 1

eine erfindungsgemäße hydraulische Maschine in Form einer Axialkolbenmaschine im axialen Schnitt;

Fig. 2

die in Fig. 1 mit X gekennzeichneter Einzelheit in vergrößerter Darstellung und

Fig. 3

einen der Fig. 2 entsprechenden Teilschnitt der Axialkolbenmaschine in abgewandelter Ausgestaltung.

The invention and further advantages which can be achieved by it are explained in more detail below with the aid of advantageous configurations and drawings. Show it

Fig. 1

a hydraulic machine according to the invention in the form of an axial piston machine in axial section;

Fig. 2

the detail marked with X in Fig. 1 in an enlarged view and

Fig. 3

one of the Fig. 2 corresponding partial section of the axial piston machine in a modified embodiment.

The hydraulic machine 1 preferably has one two-part housing 2 on, with a cup-shaped Housing part that through an end wall 2a and a Circumferential wall 2b is formed, and with a lid 2c, the abuts the end of the peripheral wall 2b facing away from the end wall 2a and thus one at least partially with a hydraulic one Fluid-filled housing interior 3 closes and with the Circumferential wall 2b is screwed detachably. A den Housing interior 3 axially with respect to the peripheral wall 2b penetrating drive shaft 5 is in the cover 2c and in the End wall 2a in at least one rolling bearing 6, 7 rotatably supported, the end wall 2a in one Through hole 8 penetrates the present Embodiment through a three-stage stepped bore is formed, in the inner and largest bore step 8a the roller bearing 7 and in its outer and smallest Bore step 8b a sealing element 9 in the form of a sealing ring each appropriate cross-sectional size is arranged.

In the housing interior 3 is on the drive shaft 5 Cylinder block 11 stored, the several, on the circumference Distributed, approximately axially extending piston bores 12, in which the piston 13 is mounted for longitudinal displacement are the cylinder block 11 towards the end wall 2a protrude and with these free piston ends on one between the end wall 2a and the cylinder block 11 arranged drive part 14 are articulated, which at respective known construction and functioning of the so formed axial piston machine rotatable or non-rotatable can be stored. In the present embodiment the drive part 14 rotatably supported, which is a Axial piston machine optionally expandable and shrinkable passage volume, in which the Drive part 14 formed by a swash plate 14a, which in a z. B. on the peripheral wall 2b and / or on the end wall 2a arranged pivot bearing 15 around a transverse to the drive shaft 5 extending pivot axis 15a is pivotally mounted, wherein the pistons 13 on one another by means of sliding shoes 17 support them facing inclined sliding surface 18.

At the end of the housing interior 3 facing away from the drive part 14 is the cylinder block 11 on a control disc 19, the is supported on the inside of the lid 2c and each other has radially opposite control kidneys 21 which in known the passage of an inlet and Outlet channel 22, 23 in the lid 2c to the respective associated hydraulic working chambers 24 in the piston bores 12 Taxes.

To set a desired volume of the Machine 1 is provided with an adjustment device 15b which the drive part 14 is adjustable, here pivotable, and can be determined in the respectively set position.

The first sealing element or sealing ring 9 is preferably around a lip ring with a different from one Base body 9a extending axially or obliquely inwards Sealing lip 9b. To secure the sealing ring 9 against axial migration outwards, it lies on a shoulder surface 25, which limits it on the outside. In the between the rolling bearing 7 and the sealing ring 9 extending space a second sealing element 26 in the form of a locking or Sealing ring arranged on its the sealing ring 9 facing side a space 27 between it and the first sealing ring 9 axially limited. The sealing element 26 is arranged in a middle bore step 8c, which after is delimited on the outside by a shoulder surface 28 on which the Sealing element 26 rests. To secure the sealing ring 9 and of the sealing element 26 against an unintentional axial Moving inwards is an axial lock provided in the present embodiment is formed in that the sealing ring 9 and that Sealing element 26 in the associated bore step 8b, 8c radial tension are pressed. In the embodiment 1 is the sealing element 26 by a locking ring, e.g. B. made of metal or plastic, which is preferably inside a play of movement to the radially adjacent component, here the drive shaft 5 or one firmly seated on it Drive shaft sleeve 5a. The movement game forms a throttle 29 or a throttled bypass 30 in the sense a compression seal 20, the function below is still explained.

One extends from the intermediate space 27 through a channel in the end wall 2a formed drainage line 31 to one Drainage space 31a, in which there is a pressure that is lower is the pressure in the inside of the second sealing element 26 arranged interior 3a, the pressure of which essentially Pressure in the housing interior 3 corresponds. The drainage space 31a can be an area of the associated hydraulic system, in which one differs only slightly from the ambient pressure There is pressure. This can e.g. B. the suction line Machine or a feed pump or auxiliary pump 4, the in the present embodiment in the lid 2c is arranged and with an associated pump element the drive shaft 5 sits and is driven by the latter. The drainage space 31a can also be a tank 33 for the hydraulic fluid of the machine 1 or one associated hydraulic system. Like Fig. 1 indicates the drainage space 31a through the Suction channel 4a of the feed or auxiliary pump 4 may be formed, with which the drainage line 31 is external Hose or pipe 34 or as an internal one Hose or pipe 34a may be formed. The latter can alongside the cylinder drum 11 through the Extend housing interior 3 and through a Plug connection be connected to the lid 2c. Both lines 34, 34a can be used for the injector effect a correspondingly designed section 4b of the Suction channel 4a can be connected.

In the present exemplary embodiments, the Sealing ring 9 and the sealing element 26 in a special Receiving ring 35 arranged in a matching Ring recess 36 of the end wall 2a is used, which for Outside of the end wall 2a is open. For axial securing of the outer cylindrical receiving ring 35 in the fitting cylindrical ring recess 36 is a securing element provided that by in the present embodiment a conventional locking ring 37 is formed, which in a Ring inner groove 38 sits in the ring recess wall and with its inside a the receiving ring 35 outside defining shoulder surface 39 forms. By a Ring recess 41 in the area of the outer edge of the Recording ring 35 is the required space for the Circlip 37 created. The receiving ring 35 limits in its installed position with the inside of the outer ring 7a of the rolling bearing 7, which on its inside by a Shoulder surface 2d of the end wall 2a is limited.

The above-described configuration with the receiving ring 35 allows on the one hand the arrangement of the sealing ring 9 and Sealing element 26 in an attachment, so that the receiving ring 35 and the sealing elements 9, 26 on the one hand are easy to use and interchangeable with the receiving ring 35 form a prefabricated attachment.

The drive shaft sleeve 5a is in relation to the one that supports it Drive shaft section through an annular seal 42 sealed. A sealing ring 43, for. B. a O-ring, very advantageous, the drive shaft section 5b sealingly surrounds and in an inner ring groove 44 in the Drive shaft sleeve 5a sits.

The drainage line 31 can partly in the housing 2 and inside of the machine 1 or through an external line 34, e.g. B. a pipe or hose can be formed. Fig. 1 shows an external line 34 connected to a z. B. radial running drainage channel 44 in the end wall 2a connected. Alternatively, the line 34 to the Extend tank 33 as indicated. The channel 44 extending from the intermediate space 27 exists from a channel section 44a, which extends to the cylindrical Shell surface of the receiving ring 35 extends in the Area one in the lateral surface of the receiving ring 35 or arranged in the inner wall of the annular recess 36 annular groove 45, of which there is a channel section 44b for line connection extends. The passage of the channel 44 through the Gap between the ring recess 36 and the Receiving ring 35 is present on both sides Ring seals 46 sealed. These are in themselves known manner each formed by a sealing ring, the in an annular groove in the inner wall of the annular recess 36 or in the lateral surface of the receiving ring (not shown) sits.

1 and 2, in the same or comparable parts with the same reference numerals is a special channel 47 forming a bypass 30 arranged in the end wall 2a, which the roller bearing 7 or bypasses the bearing bore and the housing interior 3 with connects the space 27. This alternative Design can be exclusive or in addition to above-described bypass design on the second Sealing element 26 may be present. Even with the variant a throttle 29 is provided in the channel 47, preferably within a running in the receiving ring 35 Channel section 47a. Channel 47 preferably penetrates the radial dividing line between the receiving ring 35 and the end wall 2a, the throttle 29 in the inside channel section 47a emerging from the receiving ring 35 is arranged so that it is made from this side or processed or as a separate component in the form of a Nozzle 29a can be used, e.g. B. by a Screw connection or an adhesive connection. In the front wall 2a, the channel 47 is preferably Z-shaped, the Central section 47b of the Z-shape runs radially and through a radial channel extension 47c is accessible from the outside, so that the individual channel sections are radial and axially parallel in each case from an associated outside End wall 2a can be drilled. The mouth of the with 47c denoted axially parallel channel section in the Housing interior 3 is because of a special one Breakline course not shown in Fig. 2. In the Channel extension 47c may include a closure member 48, e.g. B. in Form of a pin that can be screwed into an internal thread 49 or nozzle can be formed, with which the channel 47 optionally is lockable or in terms of its cross-sectional size is adjustable. The closure element 48 has on its outer end of a lathe tool engaging member 51 to it to screw in or out. The channel extension 47c is preferably by a closure element 48 lockable, e.g. B. by means of a screw plug 52nd

The second sealing element 26 is preferably also around a sealing ring, in particular Radial shaft seal ring, with one from a base body 26a to the interior 3a extending tubular sealing lip 26b.

The following is the function of the compression seal 20 explained in more detail.

To increase the operational safety and service life of the Sealing element 9 are permissible values of the pressure difference on Sealing element 9 required. It is also used to increase the Operational safety and service life of the sealing elements 9 and / or 26 an adequate supply of lubricant required. It ensures lubrication and cooling the sealing lips of the sealing element or elements 9 and / or 26. Zu for this purpose the hydraulic fluid to be sealed by means of the bypass 30, in which a throttle 29 is located, past the sealing element 26 into the intermediate space 27 headed. This can be a leak or a leak act targeted continuous flow rate that the Bypass 30 in the above-described embodiments enables. As an alternative to the ones described above Such a bypass 30 can also be used for exemplary embodiments a channel or a bore in the sealing element 26 itself or be formed in its sealing lip 26. Through the the throttle set-up is preferably adjustable Lubricant quantity for the sealing elements 9 and / or 26 regulated. The set amount of lubricant is like this chosen that possibly occurring and in the course of Operating time may also have increasing leaks no significant effects on the sealing element 9 or 26 on the operation of the sealing system. That as Leakage or through the associated bypass 30 in the Intermediate space 47 fluid contributes to lubrication and Cooling of the sealing elements 9 and 26. By the Pressure drop from the housing interior 3 or interior 3a to Interspace 27 or the drainage line 31 is the Lubricant supply to the sealing system ensured.

3, in the same or comparable parts with the same reference numerals only the bypass described first is preferred inner circumference of the sealing element 26 provided by formed a locking ring or a radial shaft seal can be. The channel section 47a is omitted. Against that are remaining sections of the channel 47 in the end wall 2a available in combination with one facing outwards of the rolling bearing 7 extending recess 53 a Form rinsing device 54 for the rolling bearing 7. This Flushing device 54 is in the embodiment of FIG. 1 and 2 also available.

In the context of the invention, the pressure in the Drainage line 31 or in the space 27 via a Injector can be lowered, the z. B. in the field of Suction line of the machine or the auxiliary pump 4, in particular is arranged in the area of the suction connection. The Drain opening 53 in the space 27 of the sealing system can be arranged so that the space is almost is completely filled with the hydraulic fluid.

The self-venting effect of the Sealing system. By arranging the bypass 30 and the drain line 31 is the space 27 from Machine 1 started automatically and continuously fed lubricant. This is playing especially when the machine is installed vertically (Drive shaft end with roller bearing 7 upwards) a significant one Role because the entire, above the leakage connection of the Machine 1 lying room, in which there is usually also a Drive shaft bearing 7 is located immediately after the first or Recommissioning the machine or system is completely vented automatically and thus the safe Lubricant supply, especially for the Drive shaft bearing, is ensured at all times.

Within the scope of the invention, the compression seal 20 also design as a multi-stage compression seal. Here the entire pressure difference inside the machine becomes Environment degraded in several stages. The mode of action of individual stages is analogous to that described above single stage sealing system. That in the immediate vicinity of Surrounding sealing element, here sealing element 9, takes on the actual function of complete, dust-dry waterproofing. Only the one immediately before this Gasket lying gap 27 is beyond that described Drainage line 31 with a region of low pressure Machine 1 or an associated system connected. All further seals each run over one matched bypass 30. Like the single stage Compression seal is also the multi-stage seal Compression seal self-venting.

Claims (14)

Hydraulic machine (1), in particular piston machine, with a housing (2) in which a drive shaft (5) is rotatably mounted, which passes through a housing wall (2a) in a through hole (8) and through a roller bearing (7) on the housing wall (2a) is mounted and sealed by a first sealing element (9) arranged on the outside by the roller bearing (7),
characterized,
that a second sealing element (26) is arranged in the space extending between the first sealing element (9) and the roller bearing (7), which space divides the space into an interior (3a) receiving the roller bearing (7) and between the first sealing element ( 9) and the second sealing element (26) arranged intermediate space (27), and that the intermediate space (27) is connected to a drainage line (31) in which there is a pressure which is lower than the pressure in the interior (3a). Hydraulic machine according to claim 1,
characterized,
that the first sealing element (9) and / or the second sealing element (26) each have an annular sealing lip (9b, 26b) extending towards the interior (3a). Hydraulic machine according to claim 2,
characterized,
that the second sealing element (26) is an annular body which has a throttled bypass (30) as a flow passage. Hydraulic machine according to claim 3,
characterized,
that the bypass (30) is formed by a channel (47) or by a play on the outer or inner circumference of the sealing element (26). Hydraulic machine according to claim 3 or 4,
characterized,
that the bypass (30) is formed by a passage (47) surrounding the through hole (8) at least in its longitudinal section receiving the second sealing element (26). Hydraulic machine according to claim 5,
characterized,
that a throttle (29) is arranged in the bypass (30). Hydraulic machine according to one of claims 3 to 6,
characterized,
that the bypass (30) is formed by a channel (47) extending in the second sealing element (26) or in the housing wall (2a). Hydraulic machine according to claim 7,
characterized,
that the channel (47) is accessible from the outside through a channel section (47c) opening out of the housing wall (2a). Hydraulic machine according to claim 8,
characterized,
that in the channel (47) a closure element (48) is arranged, which is adjustable between a position opening and closing the channel (47). Hydraulic machine according to claim 6,
characterized,
that at least the first sealing element (9), preferably also the second sealing element (26), are arranged in a receiving ring (35) which can be mounted on the housing wall (2a). Hydraulic machine according to claim 10,
characterized,
that the throttle (29) is arranged in an externally accessible channel section (47a) in the receiving ring (35). Hydraulic machine according to one of the preceding claims,
characterized,
that the drainage line (31) is connected to a suction line (4a) of the machine (1) or an auxiliary pump (4) or to a tank (33) of a hydraulic system associated with the machine (1). Hydraulic machine according to one of the preceding claims,
characterized,
that the drainage line (31) runs internally or externally with respect to the housing (2). Hydraulic machine according to claim 13,
characterized,
that the drainage line (31) has a conduit which penetrates the interior (3) of the housing (2) at least approximately axially parallel.

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