Abstract
A hydraulic power unit has a housing, at least one pump element, a pressure collecting plate and an electric motor. The electric motor has at least one end shield, a stator and a rotor fixed on a rotor shaft. The at least one end shield has at least one partially circumferential functional recess extending between an outer and an inner circumferential surface of the end shield in the direction of a rotor shaft bearing seat. The functional recess thus formed permits the arrangement of functional elements at a central point of the hydraulic power unit in a space-efficient manner without negatively influencing the overall size of the hydraulic power unit.
Claims
1. A hydraulic power unit, comprising: a housing; at least one pump element for delivering hydraulic fluid; a pressure collecting plate comprising a pressure channel; and an electric motor comprising: at least one end shield having a rotor shaft bearing seat and a stator holding collar, a bearing unit disposed in the rotor shaft bearing seat, the at least one end shield having at least one partially circumferential functional recess having a radial width extending partially between an outer circumferential surface and an inner circumferential surface of the at least one end shield with respect to the rotor shaft bearing seat; a stator fixed in the stator holding collar; and a rotor fixed on a rotor shaft, the rotor shaft being rotatably mounted in the bearing unit for rotation about a rotor axis; wherein the at least one partially circumferential functional recess extends around the rotor axis; wherein the at least one partially circumferential functional recess is a sensor unit receiving recess or a return flow channeling recess wherein the hydraulic fluid delivered by the pump element is brought together in the pressure channel and fed to a pressure connection.
2. The hydraulic power unit according to claim 1, wherein the at least one functional recess is open substantially over its entire surface in a direction of the pressure collecting plate.
3. The hydraulic power unit according to claim 1, wherein the at least one functional recess comprises two functional recesses, one functional recess being a sensor unit receiving recess and the other functional recess being a return flow channeling recess.
4. The hydraulic power unit according to claim 3, further comprising a sensor unit at least partially disposed in the sensor unit receiving recess.
5. The hydraulic power unit according to claim 4, further comprising a sensor disc fixed on the rotor shaft, the sensor unit detecting a speed of the rotor shaft in combination with the sensor disc.
6. The hydraulic power unit according to claim 3, wherein the return flow channeling recess comprises a return channel having a return inlet area and a return outlet area spaced from the return inlet area.
7. The hydraulic power unit according to claim 1, wherein the at least one end shield is formed separately from the housing and is attached to a mounting flange of the housing.
8. The hydraulic power unit according to claim 7, wherein the at least one end shield is mounted on the mounting flange in a vibration-damping manner.
9. The hydraulic power unit according to claim 1, wherein the at least one partially circumferential functional recess is not a bore through the at least one end shield.
10. The hydraulic power unit according to claim 1, further comprising a reservoir for the hydraulic fluid, wherein the at least one circumferential functional recess comprises the return flow channeling recess and has a return outlet area opening into the reservoir.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) In the following, the invention is explained in more detail by means of exemplary embodiment shown in the figures. Herein it is shown schematically:
(2) FIG. 1 is a perspective view of a hydraulic power unit without upper cover according to the invention;
(3) FIG. 2 is a top view of the hydraulic power unit from FIG. 1;
(4) FIG. 3 is a sectional view of the components essential to the invention along the section line A-A shown in FIG. 3;
(5) FIG. 4 is a sectional view of the components essential to the invention along the section line B-B shown in FIG. 3;
(6) FIG. 5 is a bottom view of the end shield shown in FIG. 4 with functional recesses;
(7) FIG. 6 is the view from FIG. 5 with sensor unit, sensor disc and rotor shaft;
(8) FIG. 7 is a perspective view of a pressure collection plate; and
(9) FIG. 8 is a perspective view of the pressure collecting shown in FIG. 8 and the end shield.
DETAILED DESCRIPTION OF THE INVENTION
(10) FIG. 1 shows an embodiment of a hydraulic power unit 1 without upper cover and without upper end shield.
(11) The hydraulic power unit 1 comprises a housing 2, at least one pump element (not shown), a pressure collecting plate 3 and an electric motor 4 with a lower end shield 5, see FIG. 3 The electric motor 4 also has a stator 6 and a rotor 8 fixed on a rotor shaft 7. In order to drive the at least one (not shown) pump element, the rotor shaft 7 in this embodiment is provided with an eccentric member at the corresponding end, see FIGS. 3 and 6. Here, the pump element is a radial piston pump. When configured as a gear pump, for example, the rotor shaft 7 would be provided without an eccentric member. The lower end shield 5 has a rotor shaft bearing seat 9 and a stator retaining collar 10, see FIG. 3. The stator 6 is fixed in the stator retaining collar 10 and the rotor shaft 7 is rotatably mounted in a bearing unit 11 disposed in the rotor shaft bearing seat 9.
(12) The terms “axial” and “radial” used in the following always refer to the rotor shaft 7.
(13) As shown in FIG. 1, the housing 2 comprises of a first housing element G1, a second housing element G2, a lower cover G3 and an upper cover (not shown). The use of several axially superimposed first housing elements G1 between the second housing element G2 and the upper cover is also conceivable, for example to increase the capacity of reservoir R for the hydraulic fluid formed in the interior of the housing 2. The upper cover and the upper end shield not shown in FIG. 1 allow for a view of the electric motor 4 with stator 6, rotor shaft 7 and rotor 8 arranged inside the housing 2. In this embodiment, the electric motor 4 is an under-oil electric motor. The first housing element G1 comprises four fixing holes G4 and, like the second housing element G2, a plurality of cooling fins G5. The first housing element G1 is preferably an extruded component made of aluminum or an aluminum alloy. This allows the length of the housing element G1, and thus the capacity of the reservoir R, to be adjusted variably without having to use additional housing elements G1. As further shown in FIG. 3, the second housing element G2 has fixing holes G7 for fixing the lower cover G3 as well as the first housing element G1 and the upper cover. Between the housing elements G1 and G2 and the covers G3 there are furthermore sealing members, in particular flat sealing members, which are not shown here, which seal the reservoir R formed in the interior of housing 2.
(14) FIG. 2 shows a top view of the hydraulic power unit shown in FIG. 1, in which the section lines A-A and B-B are drawn for the cross sections shown in FIGS. 3 and 4. In addition, FIG. 2 shows a connection block G6, which is used to connect the hydraulic power unit 1 to a hydraulic system. The connection block G6 has at least one return connection and at least one pressure connection, neither of which is shown here.
(15) The lower end shield 5 has an outer circumferential surface 12 and an inner circumferential surface 13, see FIG. 3 In this embodiment, the inner circumferential surface 13 is formed by the radial inner wall of the rotor shaft bearing seat 9, in which the outer ring WA of the bearing unit 11, here provided as a ball bearing, is seated. The outer circumferential surface 12 of the lower end shield 5 extends axially at essentially the same height as the inner circumferential surface 13. The inner ring WI of the bearing unit 11 is fixed on the rotor shaft 7 on one side by a stop and on the other side by a snap ring SR1.
(16) As shown in FIGS. 3 to 6, the lower end shield 5 has two partially circumferential functional recesses FA extending partially between the outer circumferential surface 12 and the inner circumferential surface 13 of the end shield 5 in the direction of the rotor shaft bearing seat 9. FIGS. 5 and 6 clearly show that “partially circumferential” here means an extension around the axis of the rotor shaft 7 which differs substantially from known recesses such as a simple bore. The difference becomes clear when comparing the mounting holes BD and BG, which will be described in detail later.
(17) FIGS. 5 and 6 show a bottom view of the end shield 5 from the pressure collecting plate 3. In this embodiment, the functional recesses FA are open over their entire surface in the direction of the pressure collecting plate 3. In this embodiment, one functional recess FA is designed as sensor unit receiving recess 14, the other as return flow channeling recess 15.
(18) A sensor unit 16 is disposed in the sensor unit receiving recess 14. As can be seen in FIGS. 4 and 6, in this embodiment the sensor unit 16 is arranged almost completely in the sensor unit receiving recess 14 in the end shield 5 and is held from below by the pressure collecting plate 3. An access recess ZA in the second housing element G2 enables the sensor unit 16 to be connected to a higher-level control system arranged outside the housing 2, not shown, for evaluation of the data recorded by the sensor unit 16, see FIG. 4.
(19) As shown in FIGS. 3, 4 and 6, a sensor disc 17 is fixed on the rotor shaft 7 by means of a snap ring SR2. Other known constructive solutions for fixing the sensor disc 17 on the rotor shaft 7 are also conceivable. The sensor disc 17 has a gearwheel-like design, is made of metal and partially overlaps with the sensor unit 16 in the axial direction, see FIG. 6. By the change between tooth and gap during the rotation of the rotor shaft 7, the sensor unit 16 can thus detect the speed of the rotor shaft 7 and transmit it to the higher-level control system.
(20) In the return flow channeling recess 15 a return channel 18 with a return inlet area RE and a return outlet area RA spaced from it is arranged. As can be seen in FIG. 4, the return flow outlet area RA opens into the reservoir R for the hydraulic fluid formed by housing 2. In this embodiment, the return channel 18 is formed integrally with the end shield 5 and forms the return flow channeling recess 15. From below, the return channel 18 is essentially completely closed off by the pressure collecting plate 3, see FIGS. 3, 4 and 8.
(21) Instead of a return channel 18, which is integrally provided with the lower end shield 5, a return channel would also be conceivable, which is designed as a separate component. In this case, the return flow channeling recess 15 could be designed geometrically variable and the return channel could be arranged in the return flow channeling recess 15 as required.
(22) As shown in FIG. 3, the lower end shield 5 is provided separately from the housing 2 and is attached to a mounting flange 19. For fastening to housing element G2, the lower end 5 shield comprises fastening holes BG. The lower end shield 5, and thus the entire electric motor 4, is fastened to the housing 2 with the appropriate screws S. The lower end shield 5 does not rest directly on the mounting flange 19, but on elastic washers 20, which ensure vibration damping of the lower end shield 5 on the mounting flange 19. Instead of the elastic washers 20, rubber buffers or rubber-bonded metals can be used alternatively for the vibration damping support.
(23) The mounting flange 19 is partially circumferential, as shown in FIG. 4, and in combination with the pressure collecting plate 3 forms a partial separation of the reservoir R. Thus, the arrangement of the return line outlet area RA above the mounting flange 19 ensures that the heated hydraulic fluid returned from the hydraulic system is returned to the reservoir R at a distance from the pump element located below the pressure plate 3, which is not shown. This ensures that the hydraulic fluid spends sufficient time within the reservoir R to cool down before being pumped back into the hydraulic system.
(24) The pressure collecting plate 3 is located below the end shield 5, see FIGS. 3, 4 and 8, and has a pressure channel 21 into which the hydraulic fluid delivered by at least one pump element located below the pressure collecting plate 3 is introduced via pressure channel inlets 22. The pressure channel 21, which is designed as a multi-core channel here, see FIG. 4, conducts the hydraulic fluid delivered by the pump element from a pressure channel outlet 23 via a not shown connecting channel through the second housing element G2 to the pressure connection in the connection block G6.
(25) As shown in FIG. 7, the pressure collecting plate 3 in this embodiment comprises a return connection channel 24, which extends in an L-shape from a return connection channel inlet 25 to a return connection channel outlet 26. Into the return connection channel inlet 25 opens a not shown connection channel which connects the return connection of the connection block G6 through the second housing element G2 to the pressure collecting plate 3. The return connection channel outlet 26 opens into the return inlet area RE of the return channel 18 in the lower end shield 5, which is located axially above the pressure collecting plate 3.
(26) Furthermore, the pressure collecting plate has 3 fixing holes BL for fixing to the lower end shield 5 by means of fixing means not shown. FIG. 7 also shows a disc-shaped recess 27 in the pressure collecting plate 3, in which the sensor disc 17 is arranged between the pressure collecting plate 3 and the lower end shield 5 in the assembled state.
LIST OF REFERENCE SIGNS
(27) 1 hydraulic power unit 2 housing 3 pressure collecting plate 4 electric motor 5 lower end shield 6 stator 7 rotor shaft 8 rotor 9 rotor shaft bearing seat 10 stator retaining collar 11 bearing unit 12 outer circumferential surface 13 inner circumferential surface 14 sensor unit receiving recess 15 return flow channeling recess 16 sensor unit 17 sensor disc 18 return channel 19 mounting flange 20 elastic washer 21 pressure channel 22 pressure channel inlet 23 pressure channel output 24 return connection channel 25 Return connection channel inlet 26 return connection channel outlet 27 disc-shaped recess BD, BG, BL mounting hole FA functional recess G1 first housing element G2 second housing element G3 Lower cover G4 fixing hole G5 cooling fin G6 connection block G7 fixing hole R Reservoir RA return outlet area RE return inlet area S screw SR1, SR2 snap ring WA outer ring of the bearing unit WI inner ring of the bearing unit ZA access recess
