The invention relates to a hydraulic device. A device of this type is known from DE 3519783, Danfoss. The drawback of the known device is that the drum sleeves slide along the first face plate at the rotational speed, with the result that the seal is insufficient and wear occurs. To avoid these drawbacks, the device is designed to comprise a housing (55, 61) with line connections (59, 92) and, inside the housing, a rotor (14), which can rotate about a first axis (1) and has pistons (12), drum sleeves (11), which can rotate about a second axis (m1, m) And have a chamber (9) in each drum sleeve, formed, inter alia, by a cylindrical wall (23) and the piston (12), it being possible for the first axis (1) to form a first angle (α) with the second axis (m1, m2), and, between the drum sleeves and the housing, a first face plate (4) with face-plate ports (3), it being possible for the face plate to form part of the housing, in such a manner that a face-plate port may be part of a first passage between a line connection and a chamber, characterized in that a drum plate (7), which can rotate with the drum sleeves (11) about the second axis (m1, m2), is arranged between the first face plate (4) and the drum sleeves (11), the drum plate (7) being provided with drum ports (6) which form part of the first passage, and each drum sleeve can be displaced across the drum plate at right angles to the second axis, in such a manner as to form a seal. This makes the sliding speed along the seal of the drum sleeve limited and means that no leaks or wear occur.
According to an improvement, the device further includes a drum plate (7) provided with a holder (18, 48) for holding the drum sleeve (s) (11) against the drum plate. This means that the drum sleeve is always connected to the drum plate in such a manner as to form a seal.
According to an improvement, the device further includes a holder comprising a clamping sleeve (48) around which the drum sleeve (11) can be slid. The result of this is that the space between the drum sleeves can be kept smaller and the diameter of the pistons can be increased, which leads to a larger displacement.
According to an improvement, the device further includes a clamping sleeve (48) secured in the drum port (6). The result of this is that the drum sleeve is secured in a simple way to the drum plate. T.F.
According to an improvement, the device further includes, in the sealing plane (8) between the drum sleeve (11) and the drum plate (7), the surface area where the oil pressure is equal to the oil pressure in the chamber (9) is smaller than the sealing surface area of the piston (12). The result of this is that the drum sleeve is pressed onto the drum plate by the pressure in the chamber, so that liquid is prevented from leaking out.
According to an improvement, the device further includes each piston (12) having a convex or arched piston ring (10), preferably designed as a ring with an opening. The result of this is that the seal between the cylindrical wall and the piston is kept in place even if abrasive particles, such as those which are found in contaminated oil, are present.
According to a further improvement, the device further includes a piston having a piston-ring groove with a first shoulder, and the piston ring, on the inner side, has a second shoulder (25), in such a manner that, under the influence of the pressure in the chamber, the second shoulder presses against the first shoulder in the axial direction, in such a manner as to form a seal. This measure reduces the force with which the piston ring presses against the cylindrical wall and means that the frictional forces are lower.
According to a further improvement, the device further includes an outer circumference of the piston ring projecting beyond the outer circumference of the piston when the inner circumference of the piston ring is resting against the piston. The result of this is that when the piston is in an inclined position in the drum sleeve, the piston ring is supported by the piston and the seal between piston ring and cylindrical wall is retained.
According to a further improvement, the device further includes a first face plate (4) or the housing and first face plate are provided with means for centering the drum plate (7). The result of this is that the drum plate is centered in a simple way.
According to another improvement, the device further includes a rotor (14) connected to a mounted shaft (2) provided with convex centering means (22) for centering the drum plate (7). The result of this is that the rotor is centered in a simple way and if appropriate the drum plate can also be centered in a simple way.
According to a further improvement, the device further includes a rotor (14) provided, on the side remote from the drum plate (7), with rotor ports (31) and with a second passage (30) for connecting the rotor port, via a piston (12), to a chamber (9), and in which the rotor ports can rotate along the housing or a second face plate (34), which is positioned in the housing and may be part of the housing, in such a manner as to form a seal. The result of this is that the axial forces on the rotor are balanced and there are scarcely any axial forces acting on the bearing means of the rotor.
According to a further improvement, the device further includes a second face plate (34) having one or more face-plate ports (33) which may be in communication with a line connection (59, 92). The result of this is that it is possible to supply and discharge the oil to and from the chambers via two different face plates. In this case, it is possible for a face-plate port at one face place to be designed to be closed over part of its circumference, so that it closes off an opening in the housing. As a result, it is possible to rotate the face plate over a greater arc length than the arc length of the face-plate port, and the control range of the device is increased in a simple way through rotation of the face plate.
According to a further improvement, the device further includes a first face plate (4) and the second face plate (34), when the rotor (14) is rotating, simultaneously opens and closes the first and second passages between chambers (9) and face-plate ports (26, 33). The result of this is that the pressure peaks which occur when the drum plates are being closed by the face plate are limited, since for each chamber the oil stream can flow along two face plates. This improves the efficiency and reduces the noise levels produced. Image Page 5
According to a further improvement, the device further includes pistons (12) and drum sleeves (11), drum plates (7) and first face plates (4) which interact therewith are arranged on both sides of the rotor (14). The result of this is that the displacement per revolution is doubled in a simple way by doubling the number of pistons, while the surface area of the face-plate ports is also doubled, so that the losses do not increase.
According to a further improvement, the device further includes a rotor (14) provided with holes (15) in which there is a rod-shaped component which is a piston (12) on both sides of the rotor. The result of this is that an accurate and stable rotor with pistons is obtained in a simple way.
According to a further improvement, the device further includes planes (V1, V2) through the first axis (1) and the two second axes (m1, m2) forming a second angle (A) with one another, where if the number of pistons on one side of the rotor is equal to n, the angle (a) is equal to (1+2k) *180° /N, where k is equal to 0 or an integer number. The result of this is that pistons on either side of the rotor alternately move past the face-plate ports, so that it is possible to count on the total number of pistons when considering the pulses in the flow of oil and torque during rotation of the rotor. Consequently, the magnitude of these pulses is reduced.
According to a further improvement, the device further includes each first face plate (4) has three or more face-plate ports (3), and the number of pistons (12) which interact with a face plate is a multiple of the number of face-plate ports. When three or more face-plate ports are used, the hydraulic device can be used as a hydraulic transformer, in which chambers are closed off by the face-plate ports while the volume in the chambers is changing greatly. If the number of pistons amounts to a multiple of the number of face-plate ports, the axial force acting on the drum plate remains more or less constant, with the result that it can rotate more smoothly and stably.
According to a further improvement, the device further includes pistons (12), each provided with a passage (27) which connects the chambers (9) on either side of the rotor (14), and the face-plate ports (3) of both first face plates (4) are designed identically in mirror-symmetrical fashion, and both first face plates are mounted in such a manner that the first passages open and close when the rotor is in different rotational positions. The result of this is that the opening and closing of corresponding chambers on both sides of the rotor does not take place at the same rotational position, with the result that torque fluctuations and pressure peaks in a chamber can be avoided. As a result, the stability and efficiency are improved.
According to one embodiment, the device further includes the surface of the drum plate (7) over which the drum sleeves (11) can slide is curved. The result of this is that during operation and in particular after the device has been at a standstill, the lubrication between drum plate and drum sleeve is improved.
According to one improvement, the device further includes the surface of the drum plate (7) over which the drum sleeves (11) can slide is conical. The result of this is that the curved surface of the drum plate is easy to produce.
According to one embodiment, the device further includes a drum sleeve (11) made by chipless deformation and has a remachined bearing surface (47) for sealing against and sliding across the drum plate (7). The result of this is that the drum sleeve can be manufactured at low cost.
According to one embodiment, the device further includes a drum sleeve (11) having a remachined bearing surface (47) for sealing against and sliding across the drum plate (7), and the bearing surface is provided with one or two concentric grooves (44, 45), if appropriate with relieving grooves (46) for delimiting the sealing surface. The result of this is that the forces acting on the drum sleeve are accurately known, with the result that the forces can be brought into equilibrium more successfully and the frictional forces are kept as low as possible.
According to one improvement, the device further includes that part of the bearing surface which rests against the drum plate (7) has a larger diameter than the diameter of the largest concentric groove (44). The result of this is that the drum sleeve cannot tilt.
According to one improvement, the device further includes corresponding face-plate ports (3) connected by means of a connection passage (54), to a common line (59, 62), and in which a connection passage is connected through a damping passage (56) to a resonance chamber (57). The result of this is that the excessive noise pollution resulting from pressure pulses which may arise as a result of resonance in the connection passages is to a significant extent suppressed, reduced or prevented.
According to one improvement, the device further includes corresponding face-plate ports (3) connected by means of a connection passage (54), to a common line (59. 62), and in which the length of the connection passages differs. The result of this is that pressure pulses which may occur as a result of resonance in the connection passages are suppressed, reduced or prevented by simple means.
The invention is explained below with reference to a number of exemplary embodiments and with the aid of a drawing, in which:
The components shown in
On the rotor shaft 2 there is a centering surface 22 about which the drum plate 7 can pivot. The centering surface 22 is convex, the centre of the convexity lying in the plane on which the centre of the convex piston rings 10 lies. The rotation of the drum plate 7 is coupled to the rotation of rotor shaft 2 by means of a key 16 which engages in a keyway. In the plane of the surface of the shaft, the key 16 has a rounding radius which is smaller than the radius of the centering surface 22, so that the key 16 does not become jammed in the keyway when the drum plate 7 rotates. If appropriate, there may be more than one key 16. It is also possible for the key 16 to be mounted in the rotor shaft 2 and for the keyway to be arranged in the drum plate 7.
On the side which faces the pistons 12, the drum plate 7 is provided with drum sleeves 11 which are clamped against the drum plate 7 by a sleeve holder 18. On the inner side, the drum sleeve 11 has a cylindrical wall 23. Each piston 12 is surrounded by a drum sleeve 11, it being possible for the piston ring 10 to move in a sealed manner along the cylindrical wall 23. The piston 12 and the cylindrical sleeve 11 therefore form a chamber 9, the volume of which changes when the rotor shaft 2 rotates. The change in volume causes oil flow into and out of the chamber 9 via a drum sleeve opening 24, a drum port 6 and a drum-plate port 3 to an opening in the housing. The corresponding drum-plate ports 3 are connected to one another in the housing. Since the axes of rotation of the rotor 14 and the drum plate 7 form an angle with respect to one another, the pistons 12 in the plane of the drum plate 7 describe an elliptical path, and the drum sleeves 11 will slide over a contact surface 8 of the drum plate 7. The holder 18 is designed with openings which allow this sliding to take place and it also ensures that the gap between drum plate 7 and drum sleeve 11 remains limited, so that pressure can build up in the chamber 9 when starting up. In another embodiment, it is also possible for the holder 18 to be secured in such a manner to the drum plate 7 that the rotation of the rotor 14 is transmitted via the pistons 12, the drum sleeves 11 and the holder 18 to the drum plate 7, with the result that the key 16 and the associated keyway can be dispensed with.
The face-plate port 3 is arranged in a face plate 4 which is supported against a surface of the housing.
This surface is not at right angles to the axis 1, but rather forms and angle therewith, thus determining the direction of the axis m1 or m2 and therefore also the rotational position at which the volume in the chamber 9 is at its minimum or maximum. The face plate 4 is secured in the housing in such a manner that it can rotate about the axis m1 or m2 and is provided over part of its circumference with toothing 5 which interacts with a pinion driven by a drive. A centering sleeve (not shown) can be used to centre the rotation of the face plate 4 in the housing in a known way. Rotation of the face plate 4 causes the setting of the hydraulic transformer to change, as described in the patent applications which were cited earlier in the text.
To keep the openings between face plate 4 and drum plate 7 small during starting up, when there is as yet no pressure in the chambers 9, there is a pressure-exerting ring 19 which is supported against the centering surface 22. Between the pressure-exerting ring 19 and a ring 21 secured in the drum plate 7 there are cup springs 20, by means of which the drum plate 7 is always pressed onto the face plate 4. If appropriate, other resilient elements may be used instead of cup springs 20.
The forces acting on the piston ring 10 are also shown in
This frictional force is greatly reduced through the fact that the inner side of the piston ring 10 is designed with a shoulder 25. If this shoulder 25 lies halfway along the width of the piston ring 10, the outwardly directed force is halved. As shown, the inwardly directed force at E is greater than the outwardly directed force. Under the influence of this, the piston ring 10 is supported on the piston 12, while as a result of the displacement of the drum sleeve 11 the seal between piston ring 10 and cylindrical wall 23 is retained all the way around. As a result of the support, the piston ring 10 exerts a resulting force R on the piston 12, and this force R drives the rotor 14.
Obviously, it is also possible for the device to be fitted without piston rings 10, but in this case it will be necessary to take measures to avoid contamination which may cause wear.
The hydraulic transformer is designed in such a manner that the pistons 12 on either side of the rotor 14 alternately move into the top dead centre, i.e. the position where the volume of the chambers 9 is at its minimum, so that in terms of fluctuations in the oil flow and the torque acting on the rotor 14, it is possible to count on the total number of pistons 12, i.e. eighteen pistons 12 in the example shown. In the exemplary embodiment shown, in which the pistons 12 on either side of the rotor 14 lie in line with one another, this is achieved by rotating the top dead centre of the pistons on one side through an angle a with respect to the top dead centre on the other side.
In this case, a is equal to half the rotational angle between two pistons 12. The face plates 4 are also rotated through this angle with respect to one another.
This is shown in
It is preferable for the rotation of the two face plates 4 to be coupled, so that only one drive is required. This is achieved, for example, by rotating the face plates 4 using a gearwheel, coupled to a shaft and coupling the two shafts to a homokinetic coupling, so that the rotation of the two face plates is accurately synchronous. If appropriate, the two face plates 4 may be provided with their own drive, so that for certain operating states a hydraulic preloading can be obtained.
The angle 3 between the axes 1 and m determines the displacement of the device. In the embodiment shown, with 9 pistons 12 on each side, the angle is 9 degrees.
If the number of pistons 12 increases, this angle has to be smaller, since otherwise the constriction of piston 12 which is required in order always to remain clear of the drum sleeve 11 becomes too great. In the embodiment shown, calculations have been based on a maximum rotational speed of the rotor 14 of 8000 revolutions per minute. If this speed is greater, a smaller angle 3 is required in order to prevent the occurrence of unacceptable pressure peaks.
In the exemplary embodiment shown, it is shown that the drum plate 7 is centered by means of the centering surface 22. It is also possible for this centering to be designed in other ways, for example by providing the drum plate 7 with a spherical bearing on its outer circumference, which is secured in the housing. Another embodiment may involve the drum plate 7 being centered with respect to the face plate 4, for example by providing the latter with a conical shape. It is also possible for a centering sleeve to be positioned in the housing in order to centre both the face plate 4 and the drum plate 7.
This makes it possible for the connection in the housing to have an opening to the face plate over a wide angle and enables the face plates to rotate through a large angle, with the result that the control range of the hydraulic transformer is increased in a simple manner through rotation of the face plate. The rotation of the face plates 26 and 28 is coupled in the manner described above.
In the exemplary embodiments given above, the device has been described as a hydraulic transformer. It will be clear to the person skilled in the art that the device can be made suitable for use as a pump or a motor with only minor adjustments, such as, inter alia, to the face plates 4 and the rotor shaft 2. Examples of this are shown in
The face plate 34 may be designed without face-plate ports. In one embodiment, there may also be face-plate ports 33, which are in communication with passages in the housing. This makes it possible to reduce pulses in the liquid flow and liquid pressure, because the flow of liquid to and from the chamber 9 take place via two face plates.
In the exemplary embodiment shown in
In the exemplary embodiments discussed above, the angles between the axes are constant and the displacement is varied through rotation of the face plates. Obviously, the design of the rotor with the fixedly mounted pistons and the drum plate with the drum sleeves which can be displaced perpendicular to the axis of the drum plate can also be used in embodiments in which the axis of the drum plate can pivot with respect to the axis of the rotor.
In the sealing surface 47, there is a groove 44 which, via a passage 46, is in communication with the outer circumference of the drum sleeve 11. This allows a film of oil to form between the drum sleeve 11 and the drum plate 7 as discussed in connection with
If appropriate, a groove 45 with a smaller diameter than the groove 44 may be arranged in the sealing surface 47. As a result, the surface area over which the decreasing pressure between the drum sleeve 11 and the drum plate 7 is active is accurately defined.
In the embodiments of the drum sleeve 11 discussed above, the drum sleeve 11 is designed as a component made from one material. If appropriate, the drum sleeve 11 may be made form two materials which are joined to one another, in which case that part of the drum sleeve 11 which forms the sealing surface 47 is made from a bronze-containing material, in order to reduce the friction. This friction results from the rotation and sliding of the drum sleeve 11 with respect to the drum plate 7. In this case, the shape of the join between the two components of the drum sleeve 11 and the elasticity of the materials are selected in such a manner that the join is closed up under the influence of the liquid pressure prevailing in the chamber 9.
In the embodiment shown in
There are two face-plate ports arranged in each face plate 4: a low-pressure port, which is connected via a connection passage 54 and a low-pressure line 59 to a low-pressure connection T, and a high-pressure port, which is connected via a connection passage 54 and a high-pressure line 62 to a high-pressure connection P.
In the embodiment shown, the connection passages 54 are of approximately equal length before they meet at 60 and pass into the low-pressure line 59 or the high-pressure line 62. The chambers 9 in the drum sleeves 11 on either side of the rotor 14 are alternately connected to the two converging connection passages 54, and therefore, in the event of unfavorable conditions, it is possible that the oil may start to resonate at 60, which can lead to pressure peaks and excessive noise in the low-pressure line 59 and/or the high-pressure line 62. There is also a risk of excessive noise when using hydraulic transformers with three pressure lines.
To limit this excessive noise, there are resonance dampers, as shown in
The pressure pulses are likewise limited in this way, albeit to a lesser extent, for example the pulses which occur in the pressure line 62 of a pump are reduced from 50 bar to pulses of 1-3 bar. However, this method has the advantage that the influence of the properties of the liquid is reduced. If appropriate, it is also possible for the resonance dampers as shown in
The designs for reducing excessive noise in the case of a double hydraulic pump or motor may, of course, also be used where necessary to reduce the pulses which may arise in a double hydraulic transformer.
In the exemplary embodiments of the hydraulic device which have been discussed above, the figures have always shown a device with drum sleeves 11 which, during rotation, describe an elliptical path and pistons 12 which describe a circular path. It will be clear to the person skilled in the art that a number of the design details discussed can also be used in other known designs, such as designs in which the drum sleeves are assembled to form a drum and the pistons are arranged in such a manner that they can be pivoted or displaced into or onto a drum, or designs in which the drum sleeves 11 can move over the face plate 4 and a drum plate 7 is not used. Other designs which can also be combined with the exemplary embodiments described here are designed with a variable displacement, for example achieved by making the angle variable.
Number | Date | Country | Kind |
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1019736 | Jan 2002 | NL | national |
1020932 | Jun 2002 | NL | national |
This application is a continuation of pending International Patent Application No. PCT/NL2003/00017 filed Jan. 10, 2003 which designates the United States and claims priority of Dutch Patent Application Nos. 1019736 filed Jan. 12, 2002 and 1020932 filed Jun. 24, 2002.
Number | Name | Date | Kind |
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3434429 | Goodwin | Mar 1969 | A |
3648567 | Clark | Mar 1972 | A |
4703682 | Hansen | Nov 1987 | A |
4776257 | Hansen | Oct 1988 | A |
5249506 | Willimczik | Oct 1993 | A |
5636561 | Pecorari | Jun 1997 | A |
Number | Date | Country |
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2 130 514 | Dec 1972 | DE |
35 19 783 | Dec 1986 | DE |
Number | Date | Country | |
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20050201879 A1 | Sep 2005 | US |
Number | Date | Country | |
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Parent | PCT/NL03/00017 | Jan 2003 | US |
Child | 10889289 | US |