Magnetic piston shoe pair for axial piston pump and motor and control method thereof

Abstract

A magnetic piston shoe pair for an axial piston pump and the motor includes: pistons, coil suites, piston shoes and a swash plate, wherein the interior of the coil suite is a closed coil; the bearing surface that the end surface of the swash plate abuts the piston shoe is provided with micro-molding holes; the micro-molding holes are hemispherical; the back surface of the swash plate is provided with a primary iron core and two secondary iron cores; the iron cores are wound with coil; the coil is connected to an external alternating current power supply. When the pump/motor is working, the coil is energized to generate a magnetic field, thereby adsorbing the piston shoe on the swash plate. Meanwhile, the coil suite generates an inductive magnetic field.

Claims

1. A magnetic piston shoe pair for an axial piston pump and a motor, comprising a primary iron core, two secondary iron cores, coils, a swash plate, micro-molding holes, an annular pressing plate, piston shoes, coil suites, pistons, cylinders, a spring, a transmission shaft, and a distributor plate, wherein the primary iron core is configured at a central position of a back surface of the swash plate; the two secondary iron cores are symmetrically distributed on both sides of the primary iron core, and respectively located between a first pressure zone and a second pressure zone of a piston pair working area; the coils are wound around the primary iron core and the secondary iron cores; and the coils are electrically connected to an external alternating current power supply.

2. The magnetic piston shoe pair for the axial piston pump and the motor according to claim 1, wherein the piston is sleeved with the coil suite, and an interior of the coil suite is a closed coil.

3. The magnetic piston shoe pair for the axial piston pump and the motor according to claim 1, wherein the micro-molding holes are configured on an annular bearing surface that the swash plate abuts the piston shoe.

4. The magnetic piston shoe pair for the axial piston pump and the motor according to claim 1, wherein the diameter and height of the secondary iron core are smaller than the primary iron core.

5. The magnetic piston shoe pair for the axial piston pump and the motor according to claim 1, wherein the micro-molding holes of the annular bearing surface of the swash plate are hemispherical.

6. A control method for the magnetic piston shoe pair for the axial piston pump and the motor according to claim 1, wherein the control method comprises: S1: when the axial piston pump or the motor starts, the coil on the primary iron core is supplied with alternating current, and the piston shoe is tightly adsorbed on an annular oblique plane of the swash plate; S2: when the piston pair is located in the first pressure zone, the coil on the secondary iron core in the first pressure zone is supplied with current, which increases an electromagnetic attractive force of the swash plate to the piston shoe, and balances an oil film thickness between the piston shoe and the swash plate; S3: when the piston pair is located in the second pressure zone, the coil on the secondary iron core in the second pressure zone is supplied with reverse current, which decreases the electromagnetic attractive force of the swash plate to the piston shoe, and balances the oil film thickness between the piston shoe and the swash plate; S4: when the oil film is too thick, the coils of the primary core and the secondary iron cores on the swash plate are energized, and two inductive magnetic field are respectively generated by the coil suite on the piston and the coils; when a gap between the swash plate and the piston shoe is too large, and the two inductive magnetic fields attract each other to reduce the oil film thickness; and S5: when the oil film is too thin, the gap between the swash plate and the piston shoe is too small, so that the two inductive magnetic fields repulse each other and increase the oil film thickness; an entire process is controlled by adjusting the current of the coil on the primary iron core.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a structural schematic diagram showing the assembly of the present invention.

(2) FIG. 2 is a partial structural schematic diagram showing the swash plate and the piston shoe pair of the present invention.

(3) FIG. 3 is a schematic diagram showing the distribution of the iron core on the back of the swash plate of the present invention.

(4) FIG. 4 is a structural schematic diagram showing the bearing surface of the swash plate of the present invention.

(5) FIG. 5 is a structural schematic diagram showing the piston shoe pair of the present invention.

(6) In the figure: 1: primary iron core; 2: secondary iron core; 3: coil; 4: swash plate; 41: first pressure zone; 42: second pressure zone; 5: micro-molding hole; 6: annular pressing plate; 7: piston shoe; 8: coil suite; 9: piston; 10: cylinder; 11: spring; 12: transmission shaft; and 13: distributor plate.

DETAILED DESCRIPTION OF THE EMBODIMENTS

(7) The technical solutions in the embodiments of the present invention are clearly and completely described below with reference to the drawings in the embodiments of the present invention. It is obvious that the described embodiments are merely a part of the embodiments of the present invention instead of all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by the persons skilled in the art without creative efforts are within the protection scope of the present invention.

(8) Referring to FIG. 1, FIG. 2, FIG. 3, FIG. 4 and FIG. 5: a magnetic piston shoe pair for an axial piston pump and a motor includes primary iron core 1, secondary iron cores 2, and coil 3, swash plate 4, micro-molding hole 5, annular pressing plate 6, piston shoes 7, coil suite 8, piston 9, cylinder 10, spring 11, transmission shaft 12, and distributor plate 13, characterized in that: the primary iron core 1 is configured on the center of the back side of the swash plate 4, and two same secondary iron cores 2 are configured at the symmetric positions on both sides of the primary iron core; the two same secondary iron cores 2, respectively located between the first pressure zone 41 and the second pressure zone 42 in the working area of the piston pair; the first pressure 41 is a low pressure zone, and the second pressure zone 42 is a high pressure zone; the primary iron core 1 and the secondary iron core 2 is wound by coils 3; the coil is connected to an external alternating current power supply; the micro-molding hole 5 is configured on the bearing surface of the swash plate.

(9) The specific working process of the control method is as follow:

(10) S1: When the axial piston pump/motor is started, the coil 3 on the primary iron core 1 is supplied with alternating current, so that the coil 3 generates an inductive magnetic field, the piston shoe pair is tightly adsorbed on the annular oblique plane of the swash plate 4, which provides a magnetic preloading of the initial motion of the piston shoe pair. Therefore, when the piston shoe 7 is to be operated, the piston shoe 7 is subject to the oil pressure in the piston cavity, the supporting force of the swash plate 4 to the piston shoe 7, and the electromagnetic force generated on the coil 3 to form a hydrostatic back-up.

(11) S2: When the piston pair is located in the first pressure zone 41, the external load force decreases, the flow of the oil through the damping hole increases, and the pressure drop generated by the damper tube also increases, resulting in a pressure decrease of the oil chamber of the piston shoe 7 and a thickness increase of the oil film. At this time, the coil 3 on the secondary iron core 2 in the first pressure zone 41 is energized, which increases the electromagnetic attractive force of the swash plate to the piston shoe, and balances the external load force by using the electromagnetic force and the hydraulic pressure, so as to prevent the oil film thickness from increasing to make the oil film balanced at a new oil film thickness.

(12) S3: When the piston pair is located in the second pressure zone 42, the external load force increases, the flow of the oil through the damping hole decreases, and the pressure drop generated by the flow of the damping pipe also decreases, resulting in a pressure increase of the oil chamber of the piston shoe 7 and a thickness decrease of the oil film. At this time, the coil 3 on the secondary iron core 2 in the second pressure zone 42 is supplied with a reverse current, which decreases the electromagnetic attractive force of the swash plate 4 to the piston shoe 7, so as to prevent the oil film thickness from decreasing to make the oil film balanced at a new oil film thickness.

(13) S4: When the oil film is too thick, an inductive magnetic field is generated by the core coil 3 on the swash plate 4 and the coil suite 8 on the piston 9 since the core coil 3 on the swash plate 4 is energized. When the oil film thickness is too thick, the gap between the swash plate 4 and the piston shoe 7 is too large, so that the two inductive magnetic fields attract each other to decrease the thickness of the oil film.

(14) S5: When the oil film is too thin, the gap between the swash plate 4 and the piston shoe 7 is too short, so that the two inductive magnetic fields repulse each other to increase the oil film thickness. The axial piston pump/motor includes a transmission shaft 12, a cylinder 10, and a distributor plate 13. One end of the transmission shaft 12 is disposed inside the cylinder 10, and is connected to the distributor plate 13; the other end passes through the swash plate 4 and the compression spring 11. At this time, the compression spring 11 merely keeps the cylinder 10 in a floating state, and ensures the hydrostatic back-up of the distributor pair rather than the spring 11 on the existing piston shoe pair to press the retainer plate, thereby effectively preventing interaction effect between the operating state of the distributor pair and the operating state of the piston shoe pair of the axial piston pump/motor, and improving the working performance of distributor pair and the piston shoe pair of the axial piston pump/motor.

(15) S6: The alternating current of the coil 3 on the primary iron core 1 can be adjusted in the whole working process of the piston shoe pair to cooperate with the above-mentioned adjustment mode, so that the piston shoe pair is always in the best working state.

(16) The bearing surface that the end surface of the swash plate 4 contacts the piston shoe 7 is provided with micro-molding holes 5. The micro-molding holes are hemispherical. The micro-molding holes 5 can sensitively provide conditions for electromagnetic force feedback and improve the oil film rigidity, which facilitates to form a hydrodynamic effect in the working process of the piston shoe pair.

(17) For the person skilled in the art, it is obvious that the present invention is not limited to the details of the above-mentioned exemplary embodiments, and the present invention can be implemented in other specific forms within the spirit or essential features of the present invention. Thus, in any case, the embodiments should be considered as exemplary and not restrictive. The protection scope of the present invention is limited by the claims instead of the above-mentioned description. Therefore, all varieties within the same meaning and scope of equivalent elements are included in the present invention. Any reference signs in the claims should not be regarded as limiting the involved claim.

(18) In addition, it should be understood that although the specification is described in terms of embodiments, not every embodiment includes only one independent technical solution. The description mode of the specification is merely used for clarity. The person skilled in the art should regard the specification as a whole. The technical solutions in the respective embodiments may also be combined appropriately to form other embodiments that can be understood by the person skilled in the art.