Plunger, plunger pump and plunger motor

Abstract

The invention relates to a hydraulic device, in particular to a plunger, a plunger pump and a plunger motor. The plunger is applied to a plunger pump or a plunger motor, the plunger is provided with a transmission groove, and the transmission groove is constructed to drive the plunger to rotate by means of medium pressure, so that a lubricating oil film is formed in a fit clearance between the plunger and a plunger hole, the possibility of dry friction is reduced, the active lubricating effect is achieved, and the service life of the plunger is prolonged. Therefore, the service life of the plunger is prolonged, and noise generated when the plunger and the plunger are matched is reduced. And meanwhile, the pressed medium actively flows along the transmission groove of the plunger, and the active flow guide effect is achieved.

Description

Technical Field

[0001] The present disclosure relates to a hydraulic device, and more particularly to a plunger, a plunger pump and a plunger motor. Background Art

[0002] The hydraulic piston pump and piston motor are mainly composed of a transmission shaft, a housing, a swash plate, a piston, a cylinder body, a spring, a bearing, a valve plate, a rear cover, etc. The piston is evenly distributed in the cylinder body along the circumference. During the transmission process, the piston reciprocates in the piston hole of the cylinder body, and at the same time, the piston rotates around the transmission shaft together with the piston hole of the cylinder body.

[0003] During this process, the plunger is subjected to complex forces and is prone to friction with the plunger hole. Especially under high-speed conditions, the mutual movement between the plunger and the plunger hole can easily destroy the oil film between the two, resulting in direct contact between the plunger and the plunger hole, forming dry friction, which seriously affects the overall service life of the plunger pump or plunger motor.

[0004] Therefore, how to ensure that the plunger can effectively reduce the wear between the plunger and the plunger hole in actual work, thereby increasing the service life of the plunger has become an urgent problem to be solved. Summary of the invention

[0005] In order to solve the problem in the prior art that dry friction easily occurs between the plunger and the plunger hole of the cylinder body, thereby causing a decrease in the overall life of the plunger and the plunger pump or plunger motor, the present disclosure provides a plunger, a plunger pump and a plunger motor.

[0006] In a first aspect, the present disclosure provides a plunger, which is applied to a plunger pump or a plunger motor. The plunger is provided with a transmission groove, and the transmission groove is configured to drive the plunger to rotate by means of a medium pressure.

[0007] In one embodiment of the present disclosure, the plunger is successively provided with a first center hole and a second center hole, wherein the second center hole is provided at an end away from the plunger where a ball head is provided, and the diameter of the first center hole is smaller than that of the second center hole, and the transmission groove is provided on the inner wall of the second center hole, and the transmission groove extends in a spiral shape along the axis.

[0008] In one embodiment of the present disclosure, the plunger comprises a cylindrical surface segment, a conical surface segment, a necked segment and the ball head which are arranged in sequence, and the second center hole is arranged in the cylindrical surface segment; The length ratio of the cylindrical surface segment to the conical surface segment is 1:2 to 1:2.2, and the ratio of the depth of the second center hole to the length of the cylindrical surface segment is 1:2 to 1:2.2.

[0009] In one embodiment of the present disclosure, the starting end of the transmission groove is located at the opening end of the second center hole, and the terminal end has a preset distance from the shoulders of the second center hole and the first center hole.

[0010] In one embodiment of the present disclosure, the center hole is continuously provided with a first center hole, a conical transition hole and a second center hole in sequence, wherein the second center hole is provided at an end away from the plunger where a ball head is provided, and the diameter of the first center hole is smaller than that of the second center hole, and the transmission groove is provided on the inner wall of the second center hole.

[0011] In one embodiment of the present disclosure, the plunger comprises a cylindrical surface segment, a conical surface segment, a necked segment and the ball head which are arranged in sequence, and the second center hole is arranged in the cylindrical surface segment; The length ratio of the cylindrical surface segment and the conical surface segment is 12:1 to 12.5:1, the ratio of the depth of the second center hole to the length of the cylindrical surface segment is 1:1 to 1:1.2, and the angle between the generatrix of the conical surface segment and the conical transition hole and the center line of the center hole is 30°.

[0012] In one embodiment of the present disclosure, there is a first preset distance between the starting end of the transmission groove and the opening end of the second center hole, and there is a second preset distance between the terminating end and the tapered transition hole.

[0013] In one embodiment of the present disclosure, at least one transmission groove is provided on the end surface of the plunger opposite to the ball head of the plunger, the transmission groove is connected to the center hole of the plunger, and the bottom of the transmission groove is inclined at a preset angle relative to the radial cross-section of the cylindrical surface segment.

[0014] In one embodiment of the present disclosure, the plunger has a plurality of the transmission grooves, and the plurality of the transmission grooves are distributed in a circular array relative to the center line of the center hole.

[0015] In one embodiment of the present disclosure, within the radial cross section of the plunger, the projection of the transmission groove is a triangle, and the vertex of the triangle points to the center hole.

[0016] In a second aspect, the present disclosure provides a plunger pump, the plunger pump comprising at least: A pump body, wherein the pump body has an oil inlet passage and an oil outlet passage; a cylinder body, the cylinder body being provided with a plunger hole and being configured to rotate relative to the pump body under the action of a drive shaft; A plunger, wherein the plunger is movably disposed in the plunger hole and is configured to reciprocate in the plunger hole under an external force to suck a medium from the oil inlet passage into the plunger hole, and after compressing the medium, discharge the medium from the oil outlet passage. The plunger is any one of the plungers described above.

[0017] In a third aspect, the present disclosure provides a plunger motor, the plunger motor comprising at least: A pump body, wherein the pump body has an oil inlet passage and an oil outlet passage; A cylinder body, wherein the cylinder body is provided with a plunger hole; The plunger is configured to reciprocate along the axial direction of the plunger hole under the push of the medium in the oil inlet circuit, and drive the cylinder body and the drive shaft to rotate. The plunger is any one of the plungers described above.

[0018] One beneficial effect of the present disclosure is that the plunger provided by the present disclosure is applied to a plunger pump or a plunger motor, the plunger is provided with a transmission groove, and the transmission groove is configured to drive the plunger to rotate by means of medium pressure, so as to form a lubricating oil film in the matching gap between the plunger and the plunger hole, reduce the possibility of dry friction, and have an active lubrication effect, thereby extending the service life of the plunger and reducing the noise generated when the two are matched. At the same time, the pressurized medium actively flows along the transmission groove of the plunger, achieving the effect of active diversion.

[0019] Other features and advantages of the present disclosure will become apparent from the following detailed description of exemplary embodiments of the present disclosure with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the present disclosure and, together with the description, serve to explain the principles of the present disclosure.

[0021] Figure 1 is a schematic diagram of the overall structure of a plunger pump provided by an embodiment of the present disclosure; Figure 2 is a schematic structural diagram of a first plunger provided by an embodiment of the present disclosure; Figure 3 yes Figure 2 Schematic diagram of the local structure at A; Figure 4 is a schematic structural diagram of a second plunger provided by an embodiment of the present disclosure; Figure 5 yes Figure 4 Schematic diagram of the local structure at B; Figure 6 is a schematic structural diagram of a third plunger provided by an embodiment of the present disclosure; Figure 7 yes Figure 6 Schematic diagram of the local structure at C; Figure 8 It is a schematic diagram of the assembly structure of the plunger and the sliding shoe provided in one embodiment of the present disclosure; Fig. 9 yes Figure 8 Schematic diagram of the end face structure.

[0022] Figures 1 to 9 The one-to-one correspondence between the component names and the reference numerals is as follows: 1. plunger; 11. center hole; 111. first center hole; 112. tapered transition hole; 113. second center hole; 12. Transmission groove; 13. Ball head; 14. Conical surface section; 15. Cylindrical surface section; 16. Neck section; 2. Plunger hole; 3. Cylinder body; 4. Pump body; 5. Slipper; 6. Swash plate; 7. Drive shaft. DETAILED DESCRIPTION

[0023] Various exemplary embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings. It should be noted that the relative arrangement of components and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present disclosure unless otherwise specifically stated.

[0024] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the present disclosure, its application, or uses.

[0025] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered as part of the specification.

[0026] It should be noted that like reference numerals and letters refer to similar items in the following figures, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0027] The specific embodiments of the present disclosure are described below in conjunction with the accompanying drawings.

[0028] In this document, “upper”, “lower”, “front”, “back”, “left”, “right”, etc. are only used to indicate the relative position relationship between related parts, rather than to limit the absolute positions of these related parts.

[0029] In this article, "first", "second", etc. are only used to distinguish each other, and do not indicate the importance and order, or the premise of each other's existence.

[0030] In this document, “equal”, “same”, etc. are not strictly limited in a mathematical and / or geometric sense, but also include errors that can be understood by those skilled in the art and are allowed in manufacturing or use.

[0031] Before describing the solution of the present disclosure in detail, for ease of understanding, it is necessary to explain the terms involved below: Dynamic lubrication: Utilize the high-speed rotation of the shaft and the viscosity of the lubricating oil to bring the lubricating oil into the wedge-shaped space and establish a pressure oil film.

[0032] Dry friction: friction that occurs when there is no lubricating medium between two contact surfaces.

[0033] Fluid friction: Friction that occurs when two contacting surfaces are completely separated by a continuous fluid lubricating film.

[0034] Boundary friction: friction that occurs when there is an extremely thin boundary film (adsorption film or reaction film) on two contacting surfaces.

[0035] Mixed friction: friction when there is a mixture of fluid friction, ordered molecular film, boundary friction and dry friction on two contacting surfaces.

[0036] For better understanding, refer to Figures 1 to 9 , the plunger structure provided by the present disclosure is specifically described in combination with four embodiments.

[0037] Embodiment 1: See also Figure 1 , since the plunger 1 has to reciprocate relative to the plunger hole 2 during operation, and at the same time the plunger hole 2 rotates around the drive shaft of the plunger pump or plunger motor, the force on the plunger 1 is relatively complex. In this process, the friction between the plunger 1 and the plunger hole 2 is essentially in a mixed friction state, especially in the area where the gap between the plunger 1 and the plunger hole 2 is small, which is between dry friction and boundary friction. In addition, once the relative speed of the plunger 1 relative to the plunger hole 2 is too large, the oil film between the two is destroyed, and the boundary friction between the plunger 1 and the plunger hole 2 will also be transformed into a dry friction state. At this time, the wear between the plunger 1 and the plunger hole 2 will accelerate, thereby affecting the life of the two.

[0038] Therefore, in order to solve the problem in the prior art that dry friction easily occurs between the plunger 1 and the plunger hole 2 of the cylinder body 3, thereby causing a reduction in the overall life of the plunger 1 and even the plunger pump or plunger motor, the present disclosure provides a plunger 1.

[0039] The plunger 1 provided in the present disclosure is provided with a transmission groove 12 , and the transmission groove 12 is configured to drive the plunger 1 to rotate by means of medium pressure.

[0040] In practical applications, the plunger 1 provided by the present disclosure is applied to a plunger pump or a plunger motor, and is installed in a plunger hole 2 of a cylinder body 3 of the plunger pump or the plunger motor.

[0041] In the case where the above plunger 1 is installed in a plunger pump, see Figure 1 When the plunger pump is started, the driving shaft 7 of the plunger pump rotates, and at the same time drives the cylinder body 3 to rotate around the driving shaft 7. The plunger 1 in the plunger hole 2 of the cylinder body 3 also rotates accordingly.

[0042] It should be noted that when the plunger pump is a swash plate type axial piston pump, the ball head of the plunger 1 is connected to the sliding shoe 5, and the sliding shoe 5 is connected to the swash plate 6. When the plunger pump is a slant axis type axial piston pump, the ball head of the plunger 1 is directly connected to the ball socket, and the ball socket is integrally designed with the drive shaft 7 or relatively fixedly arranged.

[0043] Therefore, under the action of the swash plate 6 or the ball socket of the plunger pump, the plunger 1 is forced to reciprocate along the plunger hole 2. In this process, the plunger 1 in the plunger hole 2 connected to the oil inlet line, during the relative movement with the plunger hole 2, the chamber space between the two gradually increases, thereby sucking the medium from the oil inlet line of the plunger pump into the plunger hole 2.

[0044] Subsequently, the plunger 1 and the cylinder 3 rotate with the drive. When the plunger hole 2 of the cylinder 3 is connected with the oil outlet of the plunger pump, the plunger 1 moves relative to the plunger hole 2 under the action of the swash plate 6 or the ball socket. At this time, the chamber space between the two is reduced, squeezing the medium and discharging it from the plunger hole 2, and finally discharged from the oil outlet of the plunger pump. Thus, the plunger pump converts the mechanical energy of the drive shaft 7 into hydraulic energy, realizing energy conversion.

[0045] When the plunger 1 is installed in the plunger motor, when the plunger motor is started, the medium enters the plunger hole 2 from the oil inlet of the plunger motor, pushing the plunger 1 to move relative to the plunger hole 2. At the same time, due to the action of the swash plate 6 or the ball socket, the medium will simultaneously push the plunger 1 together with the plunger hole 2 and the drive shaft 7 to rotate relative to the axis of the drive shaft 7.

[0046] When the plunger 1 and the plunger hole 2 rotate to a position where the plunger hole 2 is connected to the oil outlet passage, the medium in the plunger hole 2 is discharged from the oil outlet passage. Thus, the plunger motor converts the hydraulic energy of the medium into the mechanical energy of the drive shaft 7, thus realizing energy conversion.

[0047] See also Figure 2 , Figure 3Regardless of whether it is a plunger pump or a plunger motor, during the process of the plunger hole 2 sucking in or discharging the medium, the medium in the center hole 11 of the plunger 1 will flow due to the force. During the flow of the medium, a reaction force is applied to the plunger 1 through the transmission groove 12 of the center hole 11 of the plunger 1. A part of these reaction forces will be converted into a tangential force that drives the plunger 1 to rotate, thereby driving the plunger 1 to rotate.

[0048] Since the gap between the plunger hole 2 and the plunger 1 is not uniform, the lubricating oil distribution between the two is also uneven. When the plunger 1 rotates, due to the viscosity of the lubricating oil itself, the lubricating oil will be filled into the position where the gap between the plunger 1 and the plunger hole 2 is smaller, thereby increasing the oil film thickness between the plunger 1 and the plunger hole 2 at that location, so that the friction state between the plunger 1 and the plunger hole 2 is changed from mixed friction to fluid friction, thereby realizing dynamic pressure lubrication.

[0049] At the same time, since the lubricating oil between the plunger 1 and the plunger hole 2 is transferred from the position with a larger gap to the position with a smaller gap, the gap between the plunger 1 and the plunger hole 2 is more evenly distributed, which improves the coaxiality of the two and reduces the vibration generated by the plunger 1 during operation, thereby improving the stability of the operation of the plunger pump or plunger motor.

[0050] like Figure 2 As shown, in the plunger provided in the present disclosure, the center hole 11 is continuously provided with a first center hole 111 and a second center hole 113 in sequence, wherein the second center hole 113 is arranged at an end away from the plunger 1 where a ball head 13 is provided, and the diameter of the first center hole 111 is smaller than that of the second center hole 113, and the transmission groove 12 is arranged on the inner wall of the second center hole 113, and the transmission groove 12 extends in a spiral shape along the axis.

[0051] In practical applications, Figure 2 The plunger 1 shown is generally used in an axial piston pump of an inclined axis type. As mentioned above, the plunger 1 is connected to the ball socket. During the movement, the ball head 13 of the plunger 1 needs to rotate relative to the ball socket. In order to fully lubricate the ball head 13 and the ball socket, the plunger 1 provided by the present disclosure is provided with a center hole 11, and the center hole 11 is divided into a first center hole 111 and a second center hole 113.

[0052] Specifically, the center hole 11 is arranged along the axial direction of the plunger 1 and passes through the plunger 1. The center hole passing through the ball head 13 in the plunger 1 is the first center hole 111, and the center hole used for machining the transmission groove 12 is the second center hole 113.

[0053] When the plunger 1 is working, the medium enters the interior of the plunger 1 from the second center hole 113 , then enters the first center hole 111 , and passes through the ball head 13 , providing lubrication for the ball head 13 and the ball socket.

[0054] Considering the processing technology, the diameter of the second center hole 113 is larger than that of the first center hole 111, so as to process the transmission groove 12. At the same time, the first center hole 111 satisfies that the medium can lubricate the ball head 13 and the ball socket through the first center hole 111, so as to ensure that the overall strength of the plunger 1 will not be greatly affected by the opening of the center hole 11. The transmission groove 12 is set to be spiral, which can effectively decompose the force of the medium on the plunger 1 into a tangential force that drives the plunger 1 to rotate.

[0055] In addition, the plunger includes a cylindrical surface segment 15, a conical surface segment 14, a necked segment 16 and a ball head 13 which are arranged in sequence, and the second center hole 113 is arranged in the cylindrical surface segment 15; the length ratio of the cylindrical surface segment 15 and the conical surface segment 14 is 1:2 to 1:2.2, and the depth of the second center hole 113 and the length of the cylindrical surface segment 15 are in the ratio of 1:2 to 1:2.2.

[0056] During the operation of the plunger 1, the cylindrical surface section 15 of the plunger 1 moves in coordination with the plunger hole 2. Setting the portion where the plunger 1 and the plunger hole 2 cooperate to be cylindrical can avoid point or line contact between the plunger 1 and the plunger hole 2, thereby preventing excessive wear.

[0057] At the same time, the conical conical surface segment 14 can effectively connect the ball head 13 and the cylindrical surface segment 15 , thereby improving the overall strength of the plunger 1 .

[0058] In one embodiment, the length of the cylindrical surface segment 15 along the axial direction is 54 cm, the length of the conical surface segment 14 is 27 cm, and the depth of the second central hole 113 is 27 cm. In another embodiment, the length of the cylindrical surface segment 15 along the axial direction is 55 cm, the length of the conical surface segment 14 is 25 cm, and the depth of the second central hole 113 is 25 cm.

[0059] The plunger 1 provided by the present invention sets the ratio of the length of the cylindrical surface segment to the conical surface segment and the ratio of the depth of the second center hole 113 to the length of the cylindrical surface segment 15 between 1:2 and 1:2.2, which not only ensures the connection strength between the ball head 13 and the cylindrical surface segment 15, but also ensures that the depth of the second center hole 113 is maintained at a reasonable position, avoiding excessive influence on the overall strength of the plunger 1 due to the unreasonable depth of the second center hole 113.

[0060] like Figure 2 , Figure 3 As shown, the starting end of the transmission groove 12 is located at the opening end of the second center hole 113, and the terminal end has a preset distance from the second center hole 113 and the shoulder of the first center hole 111. At the same time, the axial length ratio of the transmission groove 12 to the second center hole 113 along the plunger 1 is 1:1.2 to 1:1.3.

[0061] In this embodiment, the transmission groove 12 is processed by a preset distance from the end of the plunger 1 away from the ball head 13, that is, the processing start end of the transmission groove 12 is the end of the plunger 1 away from the ball head 13. In one embodiment, the length of the transmission groove 12 is 20 cm, and the axial length of the second center hole 113 along the plunger 1 is 24 cm. In another embodiment, the length of the transmission groove 12 is 20 cm, and the axial length of the second center hole 113 along the plunger 1 is 26 cm.

[0062] The plunger 1 provided by the present disclosure sets the processing starting point of the transmission groove 12 at the end of the plunger 1 away from the ball head 13, and the axial length ratio of the transmission groove 12 to the second center hole 113 along the plunger 1 is maintained in the range of 1:1.2 to 1:1.3, that is, the length of the transmission groove 12 is guaranteed, so that the plunger 1 can obtain sufficient tangential force from the medium acting on the transmission groove 12 to complete the self-rotation during the working process. At the same time, the necessary tool retraction space when machining the transmission groove 12 is reserved, avoiding the second center hole 113 from being too deep, which affects the overall strength of the plunger 1.

[0063] Embodiment 2: See also Figure 4 , Figure 5 The center hole 11 is successively provided with a first center hole 111, a tapered transition hole 112 and a second center hole 113, wherein the second center hole 113 is arranged at the end away from the plunger 1 where the ball head 13 is provided, and the diameter of the first center hole 111 is smaller than that of the second center hole 113, and the transmission groove 12 is arranged on the inner wall of the second center hole 113.

[0064] In this embodiment, the center hole 11 is sequentially provided with a first center hole 111, a tapered transition hole 112, and a second center hole 113, so that when the medium contacts the plunger 1, it sequentially passes through the second center hole 113, the tapered transition hole 112, and the first center hole 111, thereby reducing the flow rate and thus reducing the leakage of the medium. At the same time, the medium is decelerated, thereby reducing the impact of the medium on the end face of the plunger 1.

[0065] In addition, the plunger 1 includes a cylindrical surface segment 15, a conical surface segment 14, a necked segment 16 and a ball head 13 which are arranged in sequence, and the second center hole 113 is arranged in the cylindrical surface segment 15; the length ratio of the cylindrical surface segment 15 and the conical surface segment 14 is 12:1 to 12.5:1, the depth of the second center hole 113 and the length ratio of the cylindrical surface segment 15 are 1:1 to 1:1.2, and the angle between the generatrix of the conical surface segment 14 and the conical transition hole 112 and the center line of the center hole 11 is 30°.

[0066] In order to enable the plunger 1 to obtain sufficient tangential force through the transmission groove 12 to rotate, the cone taper of the conical surface segment 14 and the cone transition hole 112 are set to be equal in taper, and the angle between the generatrix of the conical surface segment 14 and the cone transition hole 112 and the center line of the center hole 11 is 30°.

[0067] At this time, the depth of the second center hole 113 reaches a maximum value, which can provide more space for processing the transmission groove 12 , while making the wall thickness of the conical surface segment 14 uniform, thereby ensuring the strength of the conical surface segment 14 .

[0068] At the same time, the plunger 1 is also provided with a necking section 16 to strengthen the connection between the conical surface section 14 and the ball head 13 .

[0069] In one embodiment, the length of the cylindrical surface segment 15 is 48 cm, and the length of the conical surface segment 14 is 4 cm. In another embodiment, the length of the cylindrical surface segment 15 is 45 cm, and the length of the conical surface segment 14 is 3.6 cm.

[0070] In this embodiment, by setting the length ratio of the cylindrical surface segment 15 to the conical surface segment 14 at 12:1 to 12.5:1, the second center hole 113 can have a larger processing space when the overall length of the plunger 1 does not change, so that the processing position of the transmission groove 12 in the second center hole 113 can be more flexibly adjusted.

[0071] like Figure 4 As shown, there is a first preset distance between the starting end of the transmission groove 12 and the opening end of the second center hole 113 , and there is a second preset distance between the terminating end and the tapered transition hole 112 .

[0072] It should be noted that the starting end of the transmission groove 12 mentioned above actually refers to the processing starting end of the transmission groove 12 during the actual processing, that is, the end away from the plunger 1 where the ball head 13 is provided.

[0073] Figure 4 , Figure 5 In the embodiment, the transmission groove 12 is not directly processed at the end of the plunger 1 away from the ball head 13, but the starting processing end of the transmission groove 12 is set at a preset distance from the end of the plunger 1 away from the ball head 13. That is, the generating position of the tangential force driving the plunger 1 to rotate is set at a position closer to the ball head, which is conducive to the smooth operation of the plunger.

[0074] Embodiment three: See also Figure 6 , Figure 7In this embodiment, the structure is similar to that of the second embodiment, and the transmission groove 12 is opened on the inner wall of the second center hole 113. The difference is that the transmission groove 12 is directly processed at the end of the plunger 1 away from the ball head 13 to simplify the processing difficulty. This setting method is particularly suitable for plungers with a shorter overall length.

[0075] Embodiment 4: See also Figure 8 , Fig. 9 In this embodiment, at least one transmission groove 12 is provided on the end surface of the plunger 1 opposite to the ball head 13 of the plunger 1, the transmission groove 12 is connected to the center hole 11 of the plunger 1, and the bottom of the transmission groove 12 is inclined at a preset angle relative to the radial cross-section of the cylindrical surface segment 15.

[0076] In this embodiment, the medium enters the transmission groove 12 and acts on the groove bottom of the transmission groove 12. Since the groove bottom of the transmission groove 12 is at a preset angle with the radial cross section of the plunger 1, the force of the medium acting on the transmission groove 12 can be decomposed into the force along the axial direction of the plunger 1 and the tangential force perpendicular to the radial direction of the plunger 1. The force along the axial direction of the plunger 1 is offset by the components such as the sliding shoe 5 and the swash plate 6, while the tangential force perpendicular to the radial direction of the plunger 1 assists the plunger 1 in self-rotation.

[0077] The plunger 1 provided in the present disclosure has a transmission groove 12 disposed on the end surface of the plunger 1 and the transmission groove 12 is connected to the center hole 11 to ensure the fluidity of the medium in the transmission groove 12, thereby continuously providing tangential force to the plunger 1 through the transmission groove 12.

[0078] It should be noted that the preset angle mentioned above will affect the magnitude of the tangential force perpendicular to the radial direction of the plunger 1. In actual application, the preset angle should be in a range of greater than 45° and less than 90°, and the user can adjust it according to actual conditions.

[0079] Meanwhile, the groove bottom of the transmission groove 12 mentioned above actually refers to the contact surface in the transmission groove 12 which can decompose the force of the medium acting on the transmission groove 12 into the force along the axial direction of the plunger 1 and the tangential force perpendicular to the radial direction of the plunger 1 .

[0080] In addition, in this embodiment, the plunger also has a plurality of transmission grooves, which are distributed in a ring array relative to the center line of the center hole. The plunger 1 provided by the present disclosure is provided with a plurality of transmission grooves 12 on the end surface to enhance the self-rotation effect of the plunger 1, so that the self-rotation of the plunger 1 is more stable.

[0081] In one embodiment of the present disclosure, in the radial cross section of the plunger 1 , the projection of the transmission groove 12 is a triangle, and the vertex of the triangle points to the central hole 11 .

[0082] See also Fig. 9In one embodiment of the present disclosure, the projection of the groove bottom of the transmission groove 12 on the radial plane of the plunger 1 is triangular in shape, and one vertex of the triangular projection points to the center hole.

[0083] The purpose of such arrangement is to make the centroid of the triangular shape as far away from the axis of the plunger 1 as possible. It can be understood that in force analysis, complex forces are often converted into one point acting on an object. For the transmission groove 12, the bottom surface of the transmission groove 12 is used as the force surface. If the force on the bottom surface is analyzed, it is relatively complicated. Therefore, the centroid position of the bottom surface of the transmission groove 12 is generally used as the force analysis point, and then an imaginary concentrated force at this point replaces the force on the bottom surface of the transmission groove 12.

[0084] Therefore, in order to allow the medium to provide a greater rotational torque for the plunger 1 through the transmission groove 12, the rotational torque is the product of the tangential force and the distance between the center of mass of the bottom surface of the transmission groove 12 and the axis of the plunger 1. When the medium provides a certain tangential force for the plunger 1, the center of mass of the bottom surface of the transmission groove 12 is kept as far away from the axis of the plunger 1 as possible, thereby providing a greater rotational torque for the plunger 1.

[0085] In addition to the above four embodiments, in one embodiment of the present disclosure, the top of the ball head 13 is set to a plane. Combined with the above analysis, the ball head 13 of the plunger 1 needs to be used in conjunction with the sliding shoe 5, and the plunger 1 needs to rotate relative to the sliding shoe 5 during operation. In order to reduce the wear between the ball head 13 and the sliding shoe 5, the plunger 1 provided in the present disclosure provides oil supply between the ball head 13 and the sliding shoe 5 by setting a center hole 11. At the same time, the plunger 1 provided in the present disclosure also sets the top of the ball head 13 to a plane, so that an oil storage chamber is formed between the ball head 13 and the sliding shoe 5, so as to better provide lubrication between the ball head 13 and the sliding shoe 5.

[0086] When the medium contacts the plunger 1, the medium will act on the sliding shoe 5 along the second center hole 113, the tapered transition hole 112 and the first center hole 111. Although the impact of the medium on the end face of the plunger 1 is effectively reduced, the medium acting on the sliding shoe 5 from the first center hole 111 will impact the sliding shoe 5. The top of the ball head 13 is set as a plane, so that an oil storage chamber is formed between the plane at the top of the ball head 13 and the sliding shoe 5, and the liquid in the oil storage chamber can effectively absorb the impact of the medium on the sliding shoe 5.

[0087] In one embodiment of the present disclosure, the ratio of the depth of the transmission groove 12 to the wall thickness of the second center hole 113 is 1:7.5 to 1:11.

[0088] Considering the actual working condition of the plunger 1, due to the high pressure of the medium, if the depth of the transmission groove 12 is too deep, the wall thickness of the plunger 1 will be insufficient, thereby affecting the strength of the plunger 1. If the depth of the transmission groove 12 is too shallow, the tangential force provided by the medium through the transmission groove 12 will be insufficient, thereby affecting the self-rotation effect of the plunger 1.

[0089] Therefore, in the plunger 1 provided in the present disclosure, the ratio of the depth of the transmission groove 12 to the wall thickness of the second center hole 113 is set between 1:7.5 and 1:11. Specifically, in one embodiment, the depth of the transmission groove 12, i.e., the groove depth, is 0.4 cm, and the wall thickness of the second center hole 113 is 3 cm. In another embodiment, the groove depth of the transmission groove 12 is 0.5 cm, and the wall thickness of the second center hole 113 is 5.5 cm. In this way, the self-rotation effect of the plunger 1 is guaranteed, and the strength of the plunger 1 is guaranteed.

[0090] In the second aspect, the present disclosure provides a plunger pump, which includes a pump body 4, a cylinder body 3 and the above-mentioned plunger 1, wherein the pump body 4 has an oil inlet circuit and an oil outlet circuit, the cylinder body 3 is provided with a plunger hole 2, and is configured to rotate relative to the pump body 4 under the action of a drive shaft 7; the plunger 1 is configured to suck the medium from the oil inlet circuit into the plunger hole 2, and after compressing the medium, discharge the medium from the oil outlet circuit, and the medium cooperates with the transmission groove 12 of the plunger 1 to drive the plunger 1 to rotate.

[0091] Specifically, a driving shaft 7 is provided in the plunger pump. When the driving shaft 7 rotates, the cylinder body 3 is driven to rotate around the driving shaft 7 , so the plunger 1 in the plunger hole 2 of the cylinder body 3 also rotates accordingly.

[0092] At the same time, under the action of the swash plate 6 or the ball socket of the plunger pump, the plunger 1 is forced to perform axial reciprocating motion along the plunger hole 2. In this process, the plunger 1 in the plunger hole 2 connected to the oil inlet line, during the relative motion with the plunger hole 2, the chamber space between the two gradually increases, thereby sucking the medium from the oil inlet line of the plunger pump into the plunger hole 2.

[0093] Subsequently, the plunger 1 and the cylinder body 3 rotate with the driving shaft. When the plunger hole 2 of the cylinder body 3 is connected with the oil outlet passage of the plunger pump, the plunger 1 moves relative to the plunger hole 2 under the action of the swash plate 6. At this time, the chamber space between the two is reduced, squeezing the medium and discharging the medium from the plunger hole 2, and finally discharged from the oil outlet passage of the plunger pump.

[0094] During this process, after the medium contacts the plunger 1, the medium enters the center hole 11 of the plunger 1. Since the transmission groove 12 is provided on the inner wall of the center hole 11, the medium will apply a force to the plunger 1 through the transmission groove 12. A part of the force is offset, and the other part becomes a tangential force that drives the plunger 1 to rotate. Thus, the plunger 1 starts to rotate.

[0095] During the rotation of the plunger 1, the lubricating oil at the larger gap between the plunger 1 and the plunger hole 2 is brought to the area with smaller gap, forming a pressure oil film, thereby reducing the friction between the plunger 1 and the plunger hole 2.

[0096] In the third aspect, the present disclosure provides a plunger motor, which includes a pump body 4, a cylinder body 3 and the above-mentioned plunger 1, wherein the pump body 4 has an oil inlet circuit and an oil outlet circuit; the cylinder body 3 is provided with a plunger hole 2; the plunger 1 is configured to reciprocate axially along the plunger hole 2 under the push of the medium of the oil inlet circuit, and drive the cylinder body 3 together with the drive shaft 7 to rotate, and the medium cooperates with the transmission groove 12 of the plunger 1 to drive the plunger 1 to rotate.

[0097] Specifically, after the plunger motor is started, the medium enters the plunger hole 2 from the oil inlet passage of the plunger motor, pushing the plunger 1 to move relative to the plunger hole 2. At the same time, due to the action of the swash plate 6 or the ball socket, the medium will simultaneously push the plunger 1 together with the plunger hole 2 and the drive shaft 7 to rotate relative to the axis of the drive shaft 7. When the plunger 1 together with the plunger hole 2 rotates to a position where the plunger hole 2 is connected to the oil outlet passage, the medium in the plunger hole 2 is discharged from the oil outlet passage.

[0098] During this process, the medium contacts the plunger 1 and enters the center hole 11 of the plunger 1. Since the transmission groove 12 is provided on the inner wall of the center hole 11, the medium will apply a force to the plunger 1 through the transmission groove 12. A part of the force is offset, and the other part becomes a tangential force that drives the plunger 1 to rotate. As a result, the plunger 1 starts to rotate.

[0099] During the rotation of the plunger 1, the lubricating oil at the larger gap between the plunger 1 and the plunger hole 2 is brought to the area with smaller gap, forming a pressure oil film, reducing the friction between the plunger 1 and the plunger hole 2, and thus increasing the overall service life of the plunger motor.

[0100] For ease of understanding, the application of the plunger 1 provided in the present disclosure in a plunger pump is described in conjunction with three application scenarios.

[0101] Application scenario 1: When the user uses the plunger provided by the present disclosure in a bent axis axial piston pump, the specific structure thereof can be seen in Figures 2 to 3 The specific workflow is as follows: First, the user starts the device, which drives the driving shaft 7 in the plunger pump to rotate. The driving shaft 7 is integrally provided with the ball socket, and the ball socket is connected to the ball head of the plunger 1. Therefore, when the driving shaft 7 rotates, the plunger 1 is driven to rotate. Since the rotation center line of the plunger 1 is not parallel to the axis of the driving shaft 7, that is, the two are inclined to each other, the plunger 1 will also make axial reciprocating motion in the plunger hole 2 while rotating around the transmission shaft.

[0102] Specifically, the plunger 1 in the plunger hole 2 connected to the oil inlet circuit of the plunger pump moves away from the plunger hole 2 under the action of the ball socket, so that the cavity space between the plunger 1 and the plunger hole 2 increases, and the medium enters between the plunger 1 and the plunger hole 2 from the oil inlet circuit of the plunger pump.

[0103] Afterwards, the plunger 1 rotates with the driving shaft 7. When the plunger hole 2 corresponding to the plunger 1 is connected to the oil outlet passage of the plunger pump, the plunger 1 is squeezed by the ball socket and moves toward the plunger hole 2, so that the cavity space between the plunger 1 and the plunger hole 2 is reduced, and the medium in the plunger hole 2 is discharged through the oil outlet passage.

[0104] During this process, the medium in the plunger hole 2 enters the center hole 11 of the plunger 1, and applies a tangential force to the plunger 1 through the transmission groove 12 on the inner wall of the center hole 11, driving the plunger 1 to rotate. During the rotation of the plunger 1, the lubricating oil in the larger gap between the plunger 1 and the plunger hole 2 is brought to the area with a smaller gap, forming a pressure oil film, thereby reducing the friction between the plunger 1 and the plunger hole 2. At the same time, the medium passes through the first center hole 111 to the connection between the ball head 13 and the sliding shoe 5 to lubricate the two.

[0105] Application scenario 2: When the user uses the plunger provided by the present disclosure in a swash plate axial piston pump, the specific structure thereof can be found in Figures 4 to 7 The specific workflow is as follows: First, the user starts the device, driving the driving shaft 7 in the plunger pump to rotate, and the driving shaft 7 drives the cylinder body 3 and the plunger 1 in the plunger hole 2 of the cylinder body 3 to rotate. Since one end of the plunger 1 with a ball head 13 is connected to the swash plate 6 of the plunger pump through the sliding shoe 5, the plunger 1 rotates around the transmission shaft and, under the action of the swash plate 6, the plunger 1 also performs axial reciprocating motion in the plunger hole 2.

[0106] Specifically, the plunger 1 in the plunger hole 2 connected to the oil inlet circuit of the plunger pump is acted upon by the swash plate 6 to move away from the plunger hole 2, thereby increasing the volume space between the plunger 1 and the plunger hole 2, and thereby allowing the medium to enter between the plunger 1 and the plunger hole 2 from the oil inlet circuit of the plunger pump.

[0107] Afterwards, the plunger 1 rotates with the cylinder body 3. When the plunger hole 2 corresponding to the plunger 1 is connected to the oil outlet passage of the plunger pump, the plunger 1 is squeezed by the swash plate 6 and moves toward the plunger hole 2, so that the cavity space between the plunger 1 and the plunger hole 2 is reduced, and the medium in the plunger hole 2 is discharged through the oil outlet passage.

[0108] During this process, the medium in the plunger hole 2 enters the center hole 11 of the plunger 1, and applies a tangential force to the plunger 1 through the transmission groove 12 on the inner wall of the center hole 11, driving the plunger 1 to rotate. During the rotation of the plunger 1, the lubricating oil in the larger gap between the plunger 1 and the plunger hole 2 is brought to the area with a smaller gap, forming a pressure oil film, thereby reducing the friction between the plunger 1 and the plunger hole 2. At the same time, the medium passes through the first center hole 111 to the connection between the ball head 13 and the sliding shoe 5 to lubricate the two.

[0109] Application scenario three: See also Figure 8 , Fig. 9 In this application scenario, the plunger 1 can be used for both a bevel axis axial piston pump and a slant plate axial piston pump. The difference from the above two application scenarios is that the center hole 11 of the plunger 1 has a smaller aperture, and it is inconvenient to process the transmission groove 12 on the inner wall. Therefore, in order to realize the self-rotation of the plunger during operation, a transmission groove is set on the end face of the plunger away from the ball head.

[0110] During the operation of the axial piston pump, the medium enters the transmission groove 12 and acts on the bottom of the transmission groove 12. Since the bottom of the transmission groove 12 and the radial section of the plunger 1 are at a preset angle, the force of the medium acting on the transmission groove 12 can be decomposed into the force along the axial direction of the plunger 1 and the tangential force perpendicular to the radial direction of the plunger 1. The force along the axial direction of the plunger 1 is offset by the components such as the sliding shoe 5 and the swash plate 6, while the tangential force perpendicular to the radial direction of the plunger 1 assists the plunger 1 to rotate, thereby achieving lubrication between the plunger 1 and the plunger hole 2.

[0111] The embodiments of the present disclosure have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The choice of terms used herein is intended to best explain the principles of the embodiments, practical applications, or technical improvements in the marketplace, or to enable other persons of ordinary skill in the art to understand the embodiments disclosed herein. The scope of the present disclosure is defined by the appended claims.

Claims

1. A plunger, the plunger (1) being applied to a plunger pump or a plunger motor, characterized in that: The plunger (1) is provided with a transmission groove (12), and the transmission groove (12) is configured to drive the plunger (1) to rotate by means of medium pressure.

2. The plunger according to claim 1, characterized in that The plunger (1) is provided with a first center hole (111) and a second center hole (113) in sequence, wherein the second center hole (113) is provided at an end of the plunger (1) away from the end provided with a ball head (13), and the diameter of the first center hole (111) is smaller than that of the second center hole (113), and the transmission groove (12) is provided on the inner wall of the second center hole (113), and the transmission groove (12) extends in a spiral shape along the axis.

3. The plunger according to claim 2, characterized in that The plunger (1) comprises a cylindrical surface segment (15), a conical surface segment (14), a necked segment (16) and the ball head (13) which are arranged in sequence, and the second center hole (113) is arranged in the cylindrical surface segment (15); The length ratio of the cylindrical surface segment (15) to the conical surface segment (14) is 1:2 to 1:2.2, and the ratio of the depth of the second center hole (113) to the length of the cylindrical surface segment (15) is 1:2 to 1:2.

2.

4. The plunger according to claim 3, characterized in that The starting end of the transmission groove (12) is located at the opening end of the second center hole (113), and the ending end has a preset distance from the second center hole (113) and the shaft shoulders of the first center hole (111).

5. The plunger according to claim 1, characterized in that The plunger (1) is provided with a first center hole (111), a tapered transition hole (112), and a second center hole (113) in sequence, wherein the second center hole (113) is provided at an end of the plunger (1) away from the end provided with a ball head (13), and the diameter of the first center hole (111) is smaller than that of the second center hole (113), and the transmission groove (12) is provided on the inner wall of the second center hole (113), and the transmission groove (12) extends in a spiral shape along the axis.

6. The plunger according to claim 5, characterized in that The plunger (1) comprises a cylindrical surface segment (15), a conical surface segment (14), a necked segment (16) and the ball head (13) which are arranged in sequence, and the second center hole (113) is arranged in the cylindrical surface segment (15); The length ratio of the cylindrical surface segment (15) and the conical surface segment (14) is 12:1 to 12.5:1, the ratio of the depth of the second center hole (113) to the length of the cylindrical surface segment (15) is 1:1 to 1:1.2, and the angle between the generatrix of the conical surface segment (14) and the conical transition hole (112) and the center line of the center hole (11) is 30 degrees.

7. The plunger according to claim 6, characterized in that There is a first preset distance between the starting end of the transmission groove (12) and the opening end of the second center hole (113), and there is a second preset distance between the terminating end and the tapered transition hole (112).

8. The plunger according to claim 1, characterized in that At least one transmission groove (12) is provided on the end surface of the plunger (1) opposite to the ball head of the plunger (1); the transmission groove (12) is connected to the center hole (11) of the plunger (1), and the bottom of the transmission groove (12) is inclined at a preset angle relative to the radial cross section of the cylindrical surface segment (15).

9. The plunger according to claim 8, characterized in that The plunger (1) has a plurality of transmission grooves (12), and the plurality of transmission grooves (12) are distributed in a ring array relative to the center line of the center hole (11).

10. The plunger according to claim 8, characterized in that In the radial cross section of the plunger (11), the projection of the transmission groove (12) is a triangle, and the vertex of the triangle points to the center hole (11).

11. A plunger pump, characterized in that: The plunger pump at least comprises: A pump body (4), the pump body (4) having an oil inlet passage and an oil outlet passage; a cylinder body (3), the cylinder body (3) being provided with a plunger hole (2) and being configured to rotate relative to the pump body (4) under the action of a drive shaft (7); A plunger (1), wherein the plunger (1) is movably disposed in the plunger hole (2), and is configured to reciprocate in the plunger hole (2) under an external force so as to suck a medium from the oil inlet passage into the plunger hole (2), and after compressing the medium, discharge the medium from the oil outlet passage, wherein the plunger is the plunger according to any one of claims 1 to 10.

12. A plunger motor, characterized in that: The plunger motor at least comprises: A pump body (4), the pump body (4) having an oil inlet passage and an oil outlet passage; A cylinder body (3), wherein the cylinder body (3) is provided with a plunger hole (2); A plunger (1), the plunger (1) being movably disposed in the plunger hole (2), and being configured to reciprocate axially along the plunger hole (2) under the push of a medium in the oil inlet circuit, and to drive the cylinder body (3) and the drive shaft (7) to rotate, the plunger being the plunger according to any one of claims 1 to 10.

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