Hydraulic device
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- INNAS
- Filing Date
- 2023-06-20
- Publication Date
- 2026-06-19
AI Technical Summary
Existing hydraulic devices experience leakage due to sleeve inclination at high rotational speeds, which reduces efficiency and requires additional holding elements.
The hydraulic device incorporates actuators on the barrel plate to exert a counter force on each sleeve, balancing the centrifugal force and minimizing tilting torque, even at high rotational speeds.
This solution effectively prevents sleeve inclination and subsequent leakage, maintaining hydraulic device efficiency and eliminating the need for additional holding elements at high speeds.
Smart Images
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Abstract
Description
Technical Field
[0001] The present invention relates to a hydraulic device, comprising a housing, a shaft mounted in the housing and rotatable about a first rotation axis, the shaft having a flange extending perpendicular to the first rotation axis, and a plurality of pistons each including a spherical piston head having a respective center point, the pistons being fixed to the flange at equal angular distances about the first rotation axis and having a center line parallel to the first rotation axis, a plurality of separate sleeves, each of the pistons being movable within the sleeves, a barrel plate supporting the sleeves, the barrel plate including the sleeves being rotatable about a second rotation axis intersecting the first rotation axis at an acute angle, such that when the barrel plate including the shaft and the sleeves rotates, each of the pistons moves between a bottom dead center and a top dead center with respect to the cooperating sleeve, and the sleeve is configured such that when at least one of the pistons is at the bottom dead center under operating conditions, the centrifugal force acting on the cooperating sleeve acts radially from the second rotation axis between the barrel plate and the center point of the piston head to cause a tilting torque about the center point of the piston head.
Background Art
[0002] Such a hydraulic device is known from WO 2006 / 083163. The known hydraulic device has two barrel plates having a first side supported by respective face plates. A sleeve is placed on a second side of the barrel plate, opposite the first side. The sleeve is movable on the barrel plate in order to follow a non-circular path around a second axis of rotation under operating conditions, while the piston follows a circular path around a first axis of rotation. The path followed by the sleeve on the barrel plate also depends on a transmission between the shaft and the barrel plate, and this phenomenon is described in EP 1508694. In order to minimize friction, there is a layer of working fluid between each of the sleeves and the corresponding barrel plate. In other words, the sleeve floats on the barrel plate. Each of the piston heads fits into a cooperating sleeve, providing a sealing line between the piston head and the sleeve and thus creating a compression chamber. When the piston is at bottom dead center, the center of gravity of the sleeve is between the barrel plate and the center point of the piston head, which means that the centrifugal force on the sleeve causes an inclination torque. Due to the inclination torque, the sleeve has a tendency to tilt around the center point of the piston head, because the center point actually forms a pivot point. Although the influence of the working fluid is relatively small, the inclination torque level depends on the actual position of the center of gravity of the sleeve, including the working fluid in the sleeve, and thus the inclination torque level changes during the movement of the piston in the sleeve. When the piston moves from bottom dead center to top dead center under operating conditions, first the distance between the center of gravity and the center point of the piston head decreases. At a specific angular position of the barrel plate around the second axis of rotation, the center point of the piston head and the center of gravity of the sleeve, including the working fluid in the compression chamber, may coincide. At top dead center, the center of gravity may even be beyond the center point of the piston head as seen from the barrel plate.
[0003] In known hydraulic devices, since the diameter of the through-hole at the bottom of each sleeve is smaller than the diameter of the sleeve jacket extending from the bottom of each sleeve, the fact that the sleeve is pressed against the barrel plate through the pressure in the compression chamber partially prevents the inclination of the sleeve. The pressing force depends on this pressure and changes with the rotation of the shaft. When oil is sucked into the compression chamber during a part of the rotation of the shaft, for example, when the hydraulic pressure is relatively low, the pressing force is very small, which can lead to the inclination of the sleeve as a result of centrifugal force. This leads to a gap between the sleeve and the barrel plate, and thereby there is a possibility that oil leaks through that gap. Any leakage reduces the efficiency of the hydraulic device, which is a drawback. Therefore, known hydraulic devices are also provided with holding elements that press each sleeve against the barrel plate by individually acting spring means. The drawback of known hydraulic devices is that at high rotational speeds, the spring force is not sufficient to avoid the inclination of the sleeve. The hydraulic device described in European Patent No. 1855002 also has the same drawback.
[0004] When the shaft rotates at high speed, the inclination torque applied to each sleeve also causes the resulting inclination torque with respect to each cooperating barrel plate. This can lead to leakage between each pair of barrel plates and the face plate. SUMMARY OF THE INVENTION PROBLEM TO BE SOLVED BY THE INVENTION
[0005] An object of the present invention is to provide an improved hydraulic device. MEANS FOR SOLVING THE PROBLEM
[0006] This object is achieved by a hydraulic device according to the present invention. In the hydraulic device according to the present invention, The barrel plate is provided with a plurality of actuators for exerting a counter force on each of the respective sleeves in a certain direction and at a certain position, whereby when at least one of the pistons is at the bottom dead center under operating conditions, the counter force on the cooperating sleeve acts along a line spaced from the center point of the piston head, causing a counter torque around the center point of the piston head against the tilting torque. The actuator is controlled such that the counter force increases as the rotational speed of the barrel plate around the second rotation axis increases.
[0007] The advantage of the presence of the actuator is that the counter force is actively exerted. This means that, unlike in the case of passive spring means, the counter force does not depend on the tilting movement of the sleeve.
[0008] The actuator may be such that when the shaft operates at a constant speed, the counter force on each of the respective sleeves is substantially the same. This means that the counter force exerted by the actuator is independent of the rotational position of the shaft.
[0009] The counter force may act in the radial direction of the second rotation axis.
[0010] The counter force may be directed towards the second rotation axis.
[0011] When at least one of the pistons is at the bottom dead center, the counter force may be exerted on the corresponding sleeve at a certain position between the barrel plate and the center of the piston head.
[0012] The reaction force is preferably exerted on the sleeve at a certain distance from the barrel plate, where the center of gravity of each sleeve is located or near that position. The reason is that the centrifugal force can be balanced so that the tilting torque is minimized regardless of the rotational position of the barrel plate. The position of the centrifugal force on the sleeve containing the working fluid within the sleeve depends on the rotational position of the barrel plate, but the weight of the sleeve is greater than the weight of the working fluid within the sleeve and more or less determines the center of gravity.
[0013] The reaction force may be exerted on the outer side of the sleeve directed away from the second rotation axis. In this case, the reaction force is directed towards the second rotation axis.
[0014] Each of the actuators includes a counterweight, the counterweight being connected to the barrel plate, movable relative to the barrel plate in the radial direction of the second rotation axis, and cooperating with the corresponding sleeve through a transmission part to exert the reaction force on the corresponding sleeve. Under operating conditions, the transmission part and the counterweight may be configured such that the centrifugal force on the counterweight causes the transmission part to exert the reaction force on the corresponding sleeve. In this case, the counterweight rotates with the barrel plate, which means that the centrifugal force on the counterweight automatically increases the reaction force as the rotational speed of the barrel plate around the second rotation axis increases.
[0015] In a specific embodiment, the transmission part includes a lever mounted on the barrel plate through a pivot point having a pivot axis. The lever includes a first arm and a second arm extending in different directions from the pivot axis. The first arm cooperates with the corresponding sleeve to exert the reaction force on the corresponding sleeve. The second arm includes the counterweight. Under operating conditions, the centrifugal force on the second arm due to the counterweight causes a reaction force on the first arm against the corresponding sleeve. This is a relatively simple mechanical structure for generating the reaction force against the sleeve.
[0016] The pivot axis may extend parallel to the second rotation axis.
[0017] The pivot point includes a raised portion on one of the lever and the barrel plate, and the raised portion is supported by the other of the lever and the barrel plate, thus forming a fulcrum.
[0018] In an actual embodiment, The raised portion is provided on the lever. The barrel plate includes a ring-shaped barrel plate wall that supports the raised portion of each respective lever.
[0019] Each lever has a protrusion provided on the corresponding raised portion, and the protrusion is disposed within a cooperating hole in the barrel plate wall, or each lever has a hole provided on the corresponding raised portion, and the hole accommodates a cooperating protrusion on the barrel plate wall. The hole and the protrusion may enable pivotal movement of the lever relative to the barrel plate about the pivot axis. This configuration facilitates assembly of the lever and the barrel plate and locks the lever in its circumferential direction relative to the barrel plate.
[0020] The second arm of each lever may be partially disposed between two adjacent sleeves. This makes the hydraulic device more compact.
[0021] In an alternative embodiment, the pivot axis extends tangentially with respect to the barrel plate.
Brief Description of the Drawings
[0022] Hereinafter, the present invention will be described with reference to very schematic drawings showing embodiments of the present invention as examples.
Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
Figure 6
Mode for Carrying Out the Invention
[0023] FIG. 1 shows internal components of a hydraulic device 1 such as a pump, a hydro motor, or a hydraulic transformer, which are mounted in a housing 2 in a known manner. The hydraulic device 1 is provided with a shaft 3. This shaft 3 is supported by bearings 4 on both sides of the housing 2 and is rotatable around a first rotation axis 5. The housing 2 is provided with an opening having a shaft seal 6 on one side in a known manner, and as a result, the end of the shaft 3 protrudes from the housing 2. If the hydraulic device 1 is a pump, a motor can be connected to the end of the shaft 3, and if the hydraulic device 1 is a motor, a driven tool can be connected to the end of the shaft 3.
[0024] The hydraulic device 1 includes a face plate 7 mounted inside the housing 2 at a distance from each other. In the illustrated embodiment, the face plate 7 has a fixed position with respect to the housing 2 in its rotational direction, but in an alternative embodiment, it may be rotatable with respect to the housing 2. The shaft 3 extends through the central through-hole of the face plate 7.
[0025] The shaft 3 is provided with a flange 8 extending perpendicular to the first rotation axis 5. A plurality of pistons 9 are fixed on both sides of the flange 8 at equal angular distances around the first rotation axis 5. In this case, 14 pistons 9 are fixed on each side. Each of the pistons 9 has a modular structure, which may be different in an alternative embodiment. The piston 9 has a center line extending parallel to the first rotation axis 5. In the embodiment shown in FIG. 1, the planes of the face plate 7 are angled with respect to each other and with respect to the plane of the flange 8.
[0026] Each of the pistons 9 cooperates with a separate sleeve 10 to form a compression chamber 11 of variable volume. The hydraulic device 1 shown in FIG. 1 has 28 compression chambers 11. Each of the sleeves 10 includes a sleeve bottom 12 and a cylindrical sleeve jacket 13. The sleeve jacket 13 extends from the sleeve bottom 12. Each piston 9 is directly sealed to the inner wall of the sleeve jacket 13 through a piston head 14 having a spherical outer side including a center point.
[0027] The sleeve bottom 12 of each sleeve 10 is attached around the shaft 3 by respective ball hinges 16 and supported by respective barrel plates 15 connected to the shaft 3 by keys 17. As a result, the barrel plates 15 rotate with the shaft 3 under operating conditions. The side of each barrel plate 15 facing away from the flange 8 is supported by respective support surfaces of the face plate 7. Due to the inclined orientation of the face plate 7 with respect to the flange 8, the barrel plates 15 pivot around the ball hinges 16 during rotation with the shaft 3. The barrel plates 15 rotate around respective second rotation axes 27 that are angled at an acute angle with respect to the first rotation axis 5. This means that the sleeves 10 also rotate around the respective second rotation axes 27. As a result, when the shaft 3 is rotated, the volume of the compression chamber 11 changes.
[0028] During rotation of the barrel plates 15, each sleeve 10 performs a combined translational and pivoting movement around the cooperating piston 9. Accordingly, the outside of each piston head 14 is spherical. The spherical shape forms a seal line extending perpendicular to the center line of the cooperating sleeve 10 between the piston head 14 and the sleeve jacket 13. The diameter of each piston 9 near the flange 8 is smaller than that at the piston head 14 to allow for relative movement of the cooperating sleeve 10 around the piston 9. Under operating conditions, each of the pistons 9 moves inside the cooperating sleeve 10 between bottom dead center and top dead center. In FIG. 1, the upper piston 9 of the left barrel plate 15 is at top dead center and the lower piston 9 of the left barrel plate 15 is at bottom dead center.
[0029] The angle between the first rotation axis and the respective second rotation axes 27 is actually about 9 degrees, but may be smaller or larger.
[0030] Under operating conditions, a small layer of the working fluid exists between the bottom 12 of the sleeve and the corresponding barrel plate 15, which floats the sleeve 10 on each barrel plate 15. As a result, since the sleeve 10 moves slightly in a direction perpendicular to the second axis of rotation 27 on the barrel plate 15, the friction between the bottom 12 of the sleeve and the barrel plate 15 is minimized. This movement is described, for example, in European Patent No. 1508694.
[0031] The sleeve 10 is locked to the barrel plate 15 by the retaining element 19 in a direction parallel to the respective second axis of rotation 27. This is to hold the sleeve 10 against the barrel plate 15 at the start of the hydraulic device 1 when the hydraulic pressure still has to rise. The force of the retaining element 19 on the sleeve 10 is limited.
[0032] The barrel plate 15 is pressed against the respective face plate 7 by the spring 18. The spring 18 is mounted in the hole of the shaft 3 and presses the respective check against the face plate 7. The compression chamber 11 communicates with a cooperating passage 20 in the barrel plate 15 via the central through-hole of the respective bottom 12 of the sleeve. The passage 20 in the barrel plate 15 communicates with the high-pressure port and the low-pressure port in the housing 2 via the passage in the face plate 7.
[0033] Figures 2 to 4 show one of the barrel plate 15 and the corresponding sleeve 10 in more detail. The barrel plate 15 is provided with a plurality of actuators in the form of levers 21. The levers 21 are arranged next to their respective sleeves 10 and cooperate with their respective sleeve jackets 13. Figure 5 shows one of the levers 21 as seen from different sides. Each of the levers 21 is provided with a protrusion 22 supported by the inside of the ring-shaped barrel plate wall 23. The barrel plate wall 23 is fixed to or is part of the barrel plate 15. The contact position of the barrel plate wall 23 that supports each protrusion 22 forms a fulcrum. Each fulcrum and protrusion 22 form a pivot point of the corresponding lever 21 including a pivot axis PA extending parallel to the second rotation axis 27 (see Figures 4 and 5).
[0034] Each of the levers 21 is attached to the barrel plate wall 23 by a pin 24. The pin 24 projects from the protrusion 22 and passes through a cooperating through-hole in the barrel plate wall 23. Thereby, the lever 21 is held at a predetermined circumferential position of the barrel plate wall 23. There is sufficient play between the pin 24 and the through-hole in the barrel plate wall 23 to allow the lever 21 to tilt about the corresponding pivot axis PA. Figure 3 shows that the width of each second arm 21b of the lever 21 measured in the axial direction of the second rotation axis 27 increases from the pivot axis PA in the direction towards the free end of the second arm. The free end thereof is axially locked between the barrel plate 15 and the holding element 19 in the axial direction of the second rotation axis 21.
[0035] In an alternative embodiment (not shown), the pin 24 may be fixed to the barrel plate wall 23 while the cooperating holes may be arranged in each lever 21.
[0036] FIG. 5 shows that each of the levers 21 includes a first arm 21a and a second arm 21b that extend in different directions from the pivot axis PA. The first arm 21a cooperates with the corresponding sleeve jacket 13. The first arm 21a has a semi-cylindrical pusher 25 that contacts a side portion of the sleeve jacket 13 facing away from the second rotation axis 27. The second arm 21b is larger and heavier than the first arm 21a and forms a counterweight. FIG. 4 shows the center of gravity COG of the second arm 21b and the resulting centrifugal force Fb on the lever 21 under operating conditions. As a result, the lever 21 causes the first arm 21a to exert a reaction force Fa on the sleeve jacket 13 directed toward the second rotation axis 27. FIG. 4 shows that the centrifugal force Fb acts on the second arm 21b at a distance L1 from the pivot axis PA and the pusher 25 contacts the sleeve jacket 13 at a distance L2 from the pivot axis PA, but the distance L1 is greater than L2. This means that the reaction force Fa is greater than the centrifugal force Fb. The reaction force Fa acts on the sleeve jacket 13 at a position approximately half the axial length of the sleeve jacket 13 (see FIG. 3). It is a position at a certain distance from the barrel plate 15 where the center of gravity of the sleeve 9 is located or near it. As a result, the centrifugal force due to the inertia of the sleeve 10 on the sleeve 10 can be balanced by the reaction force Fa. This is related to minimizing the tilt torque on the sleeve 10 around the center point of the piston head 14 (which can cause the sleeve 10 to tilt and result in leakage between the sleeve bottom 12 and the barrel plate 15). The reaction force Fa increases with an increase in the rotational speed of the barrel plate 15 around the second rotation axis 27.
[0037] Figure 4 shows that each second arm 21b of the lever 21 is partially disposed between two adjacent sleeves 10. This space is available due to the cylindrical shape of the sleeve jacket 13. Each of the second arms 21b is shaped so that it does not contact the adjacent sleeve 10, i.e., the sleeve 10 with which it cooperates, and the next sleeve 10, and also so that it does not contact the barrel plate wall 23 under operating conditions. Since the sleeve 10 moves on the barrel plate 15 to slightly rotate the lever 21, there must be some play between each of the sleeve jackets 13 and the adjacent second arm 21b, and between the second arm 21b and the barrel plate wall 23. For the same reason, the first arms 21a are shaped so that they do not contact the barrel plate wall 23 under operating conditions.
[0038] Figure 6 shows a part of the barrel plate 15 of an alternative embodiment of the hydraulic device 1. This figure shows the centrifugal force Fs of the sleeve 10 directed away from the second rotation axis 27. In this embodiment, the barrel plate 15 is provided with a plurality of actuators in the form of levers 21, but the lever 21 has a pivot point 26 including a pivot axis extending in a tangential direction with respect to the barrel plate 15. The pivot axis extends perpendicular to the second rotation axis 27 and at a certain distance from the second rotation axis 27. Similar to the above-described embodiment, under operating conditions, due to the centrifugal force Fb on the second arm 21b directed away from the second rotation axis 27, the lever 21 causes the first arm 21a to exert a reaction force Fa directed towards the second rotation axis 27 on the sleeve jacket 13.
[0039] The present invention is not limited to the embodiments shown in the drawings and described above in the specification, but can be modified in different ways within the scope of the claims and their technical equivalents. For example, the reaction force may be exerted at different positions of the sleeve. However, provided that the reaction force on the cooperating sleeve acts along a line spaced from the center point of the piston head when at least one of the pistons is at bottom dead center under operating conditions, causing a counter torque around the center point of the piston head against the tilting torque, as long as the reaction force on each sleeve is exerted in a certain direction and at a certain position.
Claims
1. Hydraulic device (1), Housing (2), The housing (2) is fitted with a shaft (3) that is rotatable around a first rotation axis (5), and the shaft (3) has a flange (8) that extends perpendicularly to the first rotation axis (5). The device comprises a plurality of pistons (9), each having a spherical piston head (14) with its own center point, the pistons (9) being fixed to the flange (8) at equiangular distances around the first axis of rotation (5) and having a center line parallel to the first axis of rotation (5), It comprises multiple separate sleeves (10), and each piston (9) is movable within the sleeves (10), The barrel plate (15) supports the sleeve (10), and the barrel plate (15), including the sleeve (10), is rotatable about a second rotation axis (27) that intersects the first rotation axis (5) at an acute angle, so that when the shaft (3) and the barrel plate (15), including the sleeve (10), rotate, each of the pistons (9) moves between the bottom dead center and the top dead center relative to the corresponding sleeve (10). In a hydraulic system (1), the sleeve (10) is configured such that when at least one of the pistons (9) is at bottom dead center under operating conditions, a centrifugal force acts radially on the corresponding sleeve (10) from the second axis of rotation (27) between the barrel plate (15) and the center point of the piston head (14), causing a tilt torque around the center point of the piston head (14). The barrel plate (15) is provided with a plurality of actuators (21) for exerting a reaction force (Fa) on each sleeve (10) in a certain direction and position, so that when at least one of the pistons (9) is at bottom dead center under operating conditions, the reaction force (Fa) on the corresponding sleeve (10) acts along a line distanced from the center point of the piston head (14) to generate a counter torque around the center point of the piston head (14) against the tilt torque. The hydraulic device (1) is characterized in that the actuator (21) is controlled such that the reaction force (Fa) increases as the rotational speed of the barrel plate (15) around the second rotation axis (27) increases.
2. The hydraulic device (1) according to claim 1, wherein the actuator (21) is configured such that the reaction force (Fa) to each of the sleeves (10) is substantially the same when the shaft (3) is operating at a constant speed.
3. The hydraulic apparatus (1) according to claim 1 or 2, wherein the reaction force (Fa) acts in the radial direction of the second rotation axis (27).
4. The hydraulic apparatus (1) according to claim 3, wherein the reaction force (Fa) is directed toward the second rotation axis (27).
5. The hydraulic apparatus (1) according to claim 4, wherein when at least one of the pistons (9) is at bottom dead center, the reaction force (Fa) is exerted on the corresponding sleeve (10) at a position between the barrel plate (15) and the center of the piston head (14).
6. The hydraulic device (1) according to claim 4, wherein the reaction force (Fa) is exerted on the sleeve (10) at a certain distance from the barrel plate (15) where the center of gravity of each sleeve (10) is located, or near thereto.
7. The hydraulic apparatus (1) according to claim 1 or 2, wherein the reaction force (Fa) is exerted on the outside of the sleeve (10) which is oriented away from the second rotation axis (27).
8. Each of the actuators (21) is equipped with a counterweight, the counterweight is connected to the barrel plate and is movable relative to the barrel plate (15) in the radial direction of the second rotation axis (27), and cooperates with the corresponding sleeve (10) through the transmission unit (21) to exert the reaction force (Fa) on the corresponding sleeve (10), The hydraulic device (1) according to claim 1 or 2, wherein, under operating conditions, the transmission unit and the counterweight are configured such that the centrifugal force on the counterweight causes the transmission unit to exert the reaction force (Fa) on the corresponding sleeve (10).
9. The transmission unit includes a lever (21) mounted on the barrel plate (15) through pivot points (22, 26) having a pivot shaft (PA), The lever (21) comprises a first arm (21a) and a second arm (21b) extending in different directions from the pivot axis (PA), The first arm (21a) cooperates with the corresponding sleeve (10) to exert the reaction force (Fa) on the corresponding sleeve (10), The second arm (21b) includes the counterweight, The hydraulic device (1) according to claim 8, wherein, under operating conditions, the lever (21) causes the centrifugal force on the second arm (21b) due to the counterweight to exert the reaction force (Fa) on the first arm (21a) against the corresponding sleeve (10).
10. The hydraulic apparatus (1) according to claim 9, wherein the pivot shaft (PA) extends parallel to the second rotation shaft (27).
11. The hydraulic apparatus (1) according to claim 9, wherein the pivot point includes a raised portion (22) on one of the lever (21) and the barrel plate (15), and the raised portion (22) is supported by the other of the lever (21) and the barrel plate (15), thus forming a fulcrum.
12. The aforementioned raised portion (22) is provided on the lever (21), The hydraulic device (1) according to claim 11, wherein the barrel plate (15) comprises a ring-shaped barrel plate wall (23) that supports the raised portion (22) of each lever (21).
13. Each of the levers (21) is provided with a projection (24) on the corresponding raised portion (22), and the projection (24) is positioned in a cooperating hole in the barrel plate wall (23), or each of the levers is provided with a hole on the corresponding raised portion, and the hole accommodates the cooperating projection on the barrel plate wall. The hydraulic apparatus (1) according to claim 12, wherein the hole and the projection (24) allow the lever (21) to pivot relative to the barrel plate (15) around the pivot axis (PA).
14. The hydraulic device (1) according to claim 9, wherein the second arm (21b) of each lever (21) is partially positioned between two adjacent sleeves (10).
15. The hydraulic device (1) according to claim 9, wherein the pivot shaft (PA) extends tangentially with respect to the barrel plate (15).