Patent Application
20080128212
The present invention relates to an oil scoop assembly for the oil supply of a machine part, rotating in a stationary housing around a rotational axis and running in an oil sump, or machine parts, rotating relative to each other. The invention relates, furthermore, to a multi-disc clutch with an oil scoop assembly of the above named type.
A hydraulically actuated multi-disc clutch is known from U.S. Publication No. 2007/0193846 A1. For actuating a piston is provided, which is axially displaceable in a hydraulic chamber and which can exert an axial force onto the disc set. The hydraulic chamber is connected to a pump, which acts hydraulically on the piston. The hydraulic system comprises a joint oil filling, which serves for the actuation of the piston as well as for cooling of the disc set.
From JP 11-082537 a wet multi-disc clutch is known, which comprises an outer disc carrier, in which outer discs are held non-rotatably, and an inner disc carrier, on which the inner discs are mounted non-rotatably. On the inner disc carrier a disc with wiper arms is mounted, which, when rotating, deliver oil through axial openings of the disc into the inner chamber of the multi-disc clutch.
The present invention proposes an improved oil scoop system which ensures a reliable lubrication and cooling supply of rotating machine parts, as well as to provide especially a multi-disc clutch with improved lubricating and cooling possibilities.
The present invention proposes an oil scoop assembly for use in a stationary housing with machine parts rotatable therein relative to each other around a rotational axis, comprising an oil return element, connectable to the housing, which has a wiper for abutting an outer face of one of the machine parts; at least one channel, which is supplied with oil by the wiper and which ends in an annular channel extending coaxially to the rotational axis; and an oil scoop wheel, connectable to one of the machine parts, with a plurality of blades, distributed around the rotational axis and which extend into the annular channel and, when the oil scoop wheel rotates relative to the oil return element, deliver oil from the annular channel.
The advantage of the oil scoop assembly according to the invention is, that the machine parts, when rotating around the rotational axis, are provided reliably with oil. The embodiment with a stationary oil return element and an oil scoop wheel rotating relative thereto, is especially effective, as oil, which has reached the annular channel, is pumped by the blades of the oil scoop wheel forcibly into the inner chamber of the machine part. As the oil return element together with the wiper is held stationary in the housing, a directed oil volume flow is produced. The use of the wiper is especially advantageous, as this, when the machine part is rotating, wipes off oil, located on the outer face, and guides it in the direction towards the channel. Thus, a large oil volume flow can be delivered to the channel and, thus, finally to the rotating components, for example a multi-disc clutch.
The wiper extends preferably in an axial direction, wherein it is directed in the mounted condition along the outer face of the rotating machine part and is abutting the same. According to the preferred embodiment the wiper is formed in the cross-section blade-like or C-like, which has advantageous effects on the oil amount which can be wiped-off from the outer face. The oil scoop assembly has to be mounted in the stationary housing in such a way, that the radial channel extends generally vertically, so that the oil flows, because of the gravitational force, radially inwardly into the annular channel. Of course, also, a plurality of channels can be provided, which extend in the radial direction and end in the annular chamber.
It is contemplated that the oil scoop wheel can be connected to the same machine part, which outer face is abutted by the wiper of the oil return element. The oil return element and the oil scoop wheel act, in this case, directly together. Preferably the wiper, the channel and the annular channel form one piece and form together the oil return element. According to one embodiment the oil return element comprises a disc-like base body, on which the radial channel, the annular channel and the wiper are attached. Here, the channel is, preferably, arranged on the base body, wherein a side wall of the channel is formed by the upper face of the base body. The base body is, preferably, formed slightly conical. The annular channel has, when seen in a longitudinal section, a generally C-like profile, which is open in the direction towards the machine part, so that the blades of the oil scoop wheel can extend into the annular chamber. Preferably, the annular channel is formed by an outer annular web, an inner annular web, extending coaxially hereto, and a bottom, which is part of the base body. According to one embodiment the radial inner end of the channel ends axially neighboring the annular channel, wherein in the bottom of the annular channel a connecting through opening is provided. The through opening is, preferably, arranged in a portion of the bottom arranged radially inwardly. In this way an undercut is formed, which ensures, that oil, which has reached the annular channel, cannot escape to the outside anymore. According to one embodiment, the oil scoop wheel comprises a ring, on which the blades are attached axially projectingly. When the machine part rotates, the blades run in the annular channel around the rotational axis. The ring has, preferably, axial through openings, which are arranged in circumferential direction neighboring the blades and through which the oil is pumped by the blades in the direction towards the clutch. The blades are formed such, that they, when the oil return element rotates, deliver oil in the axial direction through the through openings. For this, they have in a radial view a blade-like shape.
According to a second variant, the oil scoop wheel is connectable to a different machine part than the machine part, which the oil return element with its wiper abuts. This variant is especially advantageous, when the axial connection possibilities on the machine part, rotating in the oil sump, are limited. Preferably, the wiper and the channel are made to form one part and form together the oil return element. The oil return element is connected according to a preferred embodiment with its channel to a connection channel formed in the housing and ending in the annular channel. Thus, in this variant the oil return element and the oil scoop wheel interact directly via the channels arranged in the housing. The annular channel is open in the housing radially inwardly, i.e. the oil supply takes place here from the annular channel into the inner chamber of the machine part arranged coaxially thereto. Preferably, the oil scoop wheel comprises a ring with radial through openings, wherein the blades project blade-like in circumferential direction, neighboring the through openings, from the ring, to deliver, when rotating in a preferred rotational direction, oil through the through openings radially inwardly.
The solution of the above named object consists, furthermore, in a multi-disc clutch with an oil scoop assembly according to the first variant, comprising an outer disc carrier with outer discs, which outer disc carrier being rotatable around a rotational axis and running in an oil sump; an inner disc carrier with inner discs, which inner disc carrier being rotatably held around the rotational axis relative to the outer disc carrier in a housing, wherein the inner discs and the outer discs are arranged axially alternatingly and form a disc set; a bottom part, formed onto one of the two disc carriers, with a plurality of circumferentially distributed axial through openings, which bottom part delimits a ring-like clutch chamber formed between the two disc carriers; an oil return element, rigidly connected to the housing, which oil return element has a wiper, abutting above the oil sump an outer face of the outer disc carrier, a channel connected to the wiper, and an annular channel connected to the channel coaxially to the rotational axis; and an oil scoop wheel, connected to the bottom part, with a plurality of blades, distributed in circumferential direction and arranged in the area of the through openings and which extend into the annular channel and, when the bottom part rotates relative to the housing, deliver oil from the annular channel through the through openings into the clutch chamber.
The multi-disc clutch according to the invention has the above named advantages of a reliable oil supply and, thus, a good lubrication and cooling, which leads to a long service-life. The use of the stationary oil return element is especially advantageous, as the gravitational force contributes to the fact, that oil flows through the radial channel from the outer end radially inwardly into the annular channel. Oil, which has reached into the annular channel, is pumped by the blades of the rotating oil scoop wheel into the inner chamber of the multi-disc clutch. By means of the wiper a large amount of oil can be wiped-off from the outer disc carrier and can be directed in the direction of the channel. The oil catcher unit used here can have, especially, any of the embodiments, named in connection with the first variant.
According to one embodiment the bottom part is rigidly connected to the outer disc carrier, i.e. especially formed integrally. The axial through openings, which connect the inner chamber of the housing to the inner chamber of the clutch, are preferably arranged in a radially inward portion of the bottom part. Thus, it is ensured, that the oil flows into the clutch radially within the inner disc carrier, so that it gets between the discs, to lubricate and to cool these. For this, the inner disc carrier is, preferably, formed sleeve-like or in form of a hollow shaft and has in the area of the disc set radial through openings, through which the oil can flow outwards to the disc set. For completeness, it shall be understood that the bottom can obviously also be connected to the inner disc carrier or formed integrally therewith. According to a preferred improvement the bottom part has radially inwardly a hub, which extends axially into the hollow shaft. Preferably, a sealing ring is provided between an end of the inner disc carrier and the bottom part. Thus, it is prevented, that the oil, flowing into the clutch chamber, flows on in the inside along the bottom radially to the outside, without getting into contact with the discs. It is rather achieved, that the oil flows within the inner disc carrier axially into the area of the disc set, to reach through the radial through openings to the discs. The oil flows, then, between the discs radially outwards and leaves the clutch chamber again through gaps arranged on the outside.
A further solution of the above named object consists in a multi-disc clutch with an oil catcher arrangement according to the second variant, comprising a housing with a sleeve portion, in which, radially inwardly, an annular channel is formed, extending coaxially to a rotational axis; an inner disc carrier with inner discs, which inner disc carrier being rotatably held in the housing around the rotational axis, wherein the inner disc carrier is formed sleeve-like and has in the area of the annular channel a plurality of circumferentially distributed radial through openings; an outer disc carrier with outer discs, which outer disc carrier being rotatably held relative to the inner disc carrier around the rotational axis and running in an oil sump, wherein the inner discs and the outer discs are arranged axially alternatingly and form a disc set; an oil return element, rigidly connected to the housing and which oil return element has a wiper abutting above the oil sump an outer face of the outer disc carrier and a channel connected to the wiper, which channel is connected to the annular channel for the oil supply; an oil scoop wheel, connected to the inner disc carrier, with a plurality of circumferentially distributed blades, which are arranged in the area of the through openings and extend into the annular channel and, when the inner disc carrier rotates relative to the housing, deliver oil from the annular channel through the through openings into the clutch chamber. This multi-disc clutch offers in analogy the same advantages, as the above named solution. The oil scoop unit, used here, can especially have each of the embodiments named in connection with the second variant.
According to one embodiment the sleeve portion has a connection channel with an outer entering opening to which the channel of the oil return element is connected and an inner exit opening ending in the annular channel. In this case, the connection channel is, in the mounted condition of the multi-disc clutch, orientated generally vertically, so that the gravitational force can be used for the oil supply. Preferably, the sleeve-like inner disc carrier has in the area of the disc set radial through openings. For the oil lubrication of the multi-disc clutch it is, especially, advantageous, when the inner diameter of the inner disc carrier increases from the plane of the first through openings in the area of the oil scoop wheel up to the plane of the second through openings in the area of the disc set. Thus, due to the centrifugal force existing when the inner disc carrier rotates, the oil automatically flows in the direction of the larger cross-section, i.e. in direction of the disc set. Also in this solution the outer disc carrier has a bottom part, preferably formed integrally therewith, with a hub, into which a shaft can be non-rotatably inserted.
According to one embodiment, which is valid for both above named variants, the outer disc carrier has a cylindrical outer face, along which the wiper extends longitudinally. In this case, the wiper is orientated generally parallel to the rotational axis, i.e. outside of the oil sump in an area above the clutch. Between the stationary wiper and the rotating outer disc carrier, a minimal gap is formed, so that frictional losses are prevented. The components of the oil scoop assembly can be manufactured for example from a plastic material, especially by an injection-moulding process, but also as form parts from metal sheet. The oil scoop wheel can be connected to the corresponding machine part, for example, by means of clipping, pressing or screwing. The oil return element is, preferably, axially supported on a shoulder arranged in the housing and, thus aligned relative to the outer disc carrier. For attaching on the housing, especially screw connections or adhesive bonding connections are possible.
These and other features and advantages of this invention will become more apparent to those skilled in the art from the detailed description of a preferred embodiment. The drawings that accompany the detailed description are described below.
The invention can be better understood on reading the following description given purely by way of example and made with reference to the accompanying drawing.
Following,
The oil return element 3, which is shown as a separate part in
It is visible, that the entering opening 8 and the through opening 9 have, respectively, a rectangular cross-section, wherein the shape of the entering opening 8 is adapted to the cross-section of the wiper 10 and is limited inwardly by a concave edge and outwardly by a convex edge, extending more or less parallel thereto. The entering opening 8 has a similar contour, which inner concave edge is adapted to the radius of the annular channel 7. The annular channel 7 has—when seen in a longitudinal sectional view—an approximately C-like profile and comprises an outer ring web 15, an inner ring web 16, extending coaxially thereto, and a bottom 17, which is formed by the base body 5. Thus, the entering opening 8 is formed on a portion of the bottom 17 arranged radially inwards, i.e. neighboring the inner ring web 16, so that oil, which has reached the annular channel 7, cannot flow back into the radial channel 6 because of the centrifugal forces. The annular channel 7 is open in the axial direction towards the machine part, so that the oil can be delivered by the oil scoop wheel 4 from the thus formed annular opening 18 into the interior of the machine part for cooling and lubrication purposes.
The radial channel 6 is arranged on the disc-like base body 5, wherein the side wall of the channel 6, facing the machine part, is formed by the upper face of the base body 5. The disc-like base body 5 is formed slightly conical, so that the channel 6 ends axially neighboring relative to the annular channel 7, wherein the entering opening 8 and the annular opening 18 are arranged on a common plane. Radially outwards, the base body 5 has a flange portion 19 for the axial support on a corresponding radial shoulder of the housing. For the rotational locking, at least one bore 20, into which a not shown screw is inserted and which can be screwed into a corresponding threaded bore in the housing, is provided in the flange portion 19. The oil return element 3 is molded integrally with the wiper 10, the channel 6 and the annular channel 7 from a plastic material, wherein other materials are not excluded.
The oil scoop wheel 4, which is shown as a separate component in
The multi-disc clutch 33 comprises two components, rotatable relative to each other around the rotational axis A, namely an outer disc carrier 26, in which outer discs 37 are non-rotatably and axially movable accommodated, and an inner disc carrier 38, on which the inner discs 39 are held non-rotatably and axially movable. The outer discs 37 and the inner discs 39 are arranged axially alternatingly and form together a disc set 40. The inner disc carrier 38 is formed as a hollow shaft, which has at its free end a flange 42 for connecting to a not shown drive train. In the area of the disc set 40, several radial through openings 41 are provided in the hollow shaft, through which cooling oil, delivered to the interior of the multi-disc clutch 33, can reach the clutch discs 37, 39. The inner disc carrier 38 is held rotatably around the rotational axis A relative to the housing 35 by means of a radial bearing 43 and is axially supported by means of an axial bearing 44 relative to the housing 35. For sealing purposes, a radial shaft sealing ring 45 sits between the housing 35 and the inner disc carrier 38. The outer disc carrier 36 is formed cup-shaped and comprises a cylindrical envelope portion, a bottom 46 and a hub 47 with an inner toothing. Into the hub 47, a not shown connection shaft can be inserted non-rotatably, which is to be held with its free end in a bore 49 of the inner disc carrier 38, which bore 49 is provided with the radial bearing 48. The envelope portion, the bottom 46 and the hub 47 are formed integrally and form together the cage of the multi-disc clutch 33.
The disc set 40 is axially supported on a support disc 50, which is fixedly connected to the inner disc carrier 38 and which again is axially supported on a securing ring 52, inserted into an annular groove of the inner disc carrier 38. The disc set 40 is axially acted upon by a pressure disc 53, which is held in a corresponding recess of a pressure plate 54. Between the pressure plate 54 and the inner disc carrier 38, spring means 55 in form of Belleville spring washers are active, which act upon the pressure plate 54 and the disc set 40 in axial opposite directions, i.e. are effective in the sense of releasing the disc clutch 33. The spring means 55 are axially supported on a securing ring 56, fixed relative to the inner disc carrier 38. Between the bottom 46 of the outer disc carrier 36 and the end of the inner disc carrier 38, neighboring the same, a sealing ring 51 in form of a plastic ring is inserted, which prevents, that cooling oil, delivered into the clutch cage, flows on the inside of the bottom radially to the outside, without contacting the disc set. A further purpose of the plastic ring 51 is to hold the outer disc carrier 36 at an axial distance to the inner disc carrier 38.
To cool and to lubricate the multi-disc clutch 33, the oil scoop assembly 2 is provided, which delivers oil from the oil sump arranged in the housing 35 into the interior of the multi-disc clutch 33. It is visible, that the oil return element 3 with its flange portion 19 is axially supported on a radial shoulder 27 of the housing 35 and is fixed by at least one screw connection 28 to the housing 35. In this case, the screw connection 28 serves also as a rotational retainment, so that it is ensured, that the wiper 10 is always held in the upper portion of the housing 35 and that the channel 6 is directed vertically downwards. The annular channel 7 is arranged coaxially to the rotational axis A of the multi-disc clutch 33 and forms a central bore 29, through which the shaft, to be connected non-rotatably to the hub 47, can be passed. The oil scoop wheel 4 is mounted with its annular disc 22 to the bottom 46 of the outer disc carrier 36, i.e. preferably screwed. The screws 30, which are visible in
It is visible, that the oil return element 3 is fixed in such a way in the housing 35, that the wiper 10 is aligned parallel to the longitudinal axis A and, thus, along the outer face of the outer disc carrier 36. In this way it is achieved, that oil, sticking to the outer face 21 of the outer disc carrier 36 after running through the oil sump, is wiped-off by the wiper 10 and is guided to the entering opening 8 into the channel 6. To be able to guide as much oil as possible into the channel 8, the wiper 10 extends in the axial direction along the largest part of the outer disc carrier 36. For the largest possible oil volume flow it is further provided, that the oil return element 3 is held in the housing 35 in such a way, that the radial gap formed between the wiper 10 and the outer disc carrier 36 is minimal. But, a touching contact between the wiper 10 and the cylindrical outer face of the outer disc carrier 36 should be prevented, to prevent frictional losses.
The path of the cooling oil flow is shown in
The axial actuating device 34, provided for actuating the disc clutch 33, is formed in the shape of a ball ramp assembly, whereas other actuation mechanisms, as for example hydraulic actuators, are also possible.
The ball ramp arrangement 34 comprises two discs, rotatable relative to each other, namely a support disc 57 and a setting disc 58, of which the support disc 57 is axially supported relative to the stationary housing 35 and of which the setting disc 58 is axially displaceable. The two discs 57, 58 have in their end faces, facing each other, several circumferentially distributed ball grooves 59, 60 with gradients of opposite directions. Respectively, two ball grooves 59, 60, arranged opposite each other and extending in circumferential direction, form a pair and take-up, respectively, one ball, on which the discs 57, 58 are axially supported. The balls are held in circumferential direction in a cage 62, held axially between the two discs 57, 58. Here the balls are not visible, as they are arranged outside the shown sectional plane. The depth of one pair of ball grooves 59, 60 is variable along the circumference, so that a rotation of the discs 57, 58 relative to each other leads to an axial displacement and thus, to an actuation of the pressure plate 54 of the disc clutch 33. In this case, the support disc 57 rests in a recess of the housing 35 in a non-rotational manner. The setting disc 58 is radially held by means of the balls, resting in the ball grooves relative to the support disc 57 and can be rotatably driven by means of a toothed segment 63 around the rotational axis A. Axially between the setting disc 58 and the pressure plate 54, an axial bearing 64 is interconnected, which enables a transmission of the axial forces with simultaneous relative rotational movement.
When the frictional clutch is completely released, the two discs 57, 58 are arranged in the most possible approximate position relative to each other. When rotating the setting disc 58 in a corresponding manner, the balls run in the ball grooves 12, 13 in areas of lower depth. Thus, an expansion takes place between the discs 57, 58, wherein the setting disc 58 is moved axially in the direction towards the disc set 40 and acts thereupon via the axial bearing 64 and the pressure plate 54. Corresponding to the rotation of the setting disc 58, the disc clutch 33 is locked to a predetermined extent, and a coupling of the outer disc carrier 36 to the inner disc carrier 38 is achieved. The spring means 55, formed as Belleville spring washers, cause, that the setting disc 58 is displaced again into its original starting position in the direction of the support disc 57, when the electromotor 61 is not actuated.
The ball ramp assembly 34 can be driven via a step-down transmission by the electromotor 61, which is flange-mounted on the housing 35. The step-down transmission comprises a pinion 65 with two straight toothings 66, 67, which is rotatably mounted on a bolt 68 parallel to the rotational axis A. The straight toothing 66 of larger diameter is meshing with the drive shaft 69 of the electromotor 61, while the straight toothing 67 of smaller diameter meshes with the tooth segment 63 of the adjustment disc 58. The bolt 68 rests with one end in a bore of the housing 35 and is held with its second end in a lid 70 inserted into the housing 35. The lid 70 sits in a bore of the housing 35 in a sealed manner.
In the following
The oil return element 3′ shown in
The oil scoop wheel 4′, which is shown as a separate part in
In the following
Here, the longitudinal sectional view through the clutch 32′ is selected such, that the electromotor 61′ can be seen in the lower half of the drawing, wherein the structure and function is identical to that of
The inner disc carrier 38′ is formed to a greatest extent in the form of a hollow shaft, on which clutch-sided first end, the inner discs 39′ are non-rotatably mounted, and on which opposite second end, a flange 42′ for connecting to a not shown drive train is provided. In the axial overlapping area with the annular channel 7′, the inner disc carrier 38′ has a plurality of radial first through openings 31′, circumferentially distributed, and which end in a cavity 77, formed in the sleeve-like inner disc carrier 38. The cavity 77 is axially closed by a web 78 in the direction towards the flange 42′. In the area of the disc set 40′ a plurality of radial second through openings 41 are provided in the inner disc carrier 38, through which the cooling oil, delivered into the cavity 77, can reach the clutch discs 37′, 39′. It is visible, that the cavity 77 opens cone-like starting from the entry area of the first through openings 31′ in the direction towards the second through openings 41′. By means of this layout it is achieved, that the oil, which got into the cavity 77 through the through openings 31′, flows, when the inner disc carrier 38′ rotates, because of the centrifugal forces in the direction towards the second through openings 41′. In an area axially neighboring the hub 47′, the inner disc carrier 38′ has a bearing portion 79, in which the shaft, connected non-rotatably to the hub 47′, is to be rotatably received by means of a bearing 48′ concerning the rotational axis A. So that the oil, which is in the cavity 77, can flow in the direction towards the second through openings 41′, the bearing portion 79 has at least one axially extending transfer channel 76.
The path of the cooling oil flow is shown in
The foregoing invention has been described in accordance with the relevant legal standards, thus the description is exemplary rather than limiting in nature. Variations and modifications to the disclosed embodiment may become apparent to those skilled in the art and do come within the scope of the invention. Accordingly, the scope of legal protection afforded this invention can only be determined by studying the following claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2006 055 808.1 | Nov 2006 | DE | national |
