A discrete cylinder swash plate type swash plate piston pump

Abstract

The application discloses a discrete cylinder swing plate type swash plate plunger pump, and belongs to the technical field of plunger pumps; the discrete cylinder swing plate type swash plate plunger pump adopts a floating plate design, cancels a single sliding shoe in a traditional plunger pump, and all plungers are installed on the floating plate; the floating plate has a larger cooperation surface with the swash plate, and the generated oil film is more stable; and an integral sealing belt is adopted to ensure that the sliding speed of the inner and outer sealing belts on the swash plate is stable, the temperature rise of oil caused by shearing force and pressure difference is consistent, the sliding shoe deflection caused by different temperature rises of oil is avoided, and the anti-overturning capability is stronger; a central universal joint is adopted to limit the relative position between the two floating pressure plates; since the universal joint can swing without changing the relative position of the two components, the positioning effect is good; and the traditional cylinder is discretized; each discrete cylinder can follow the swing of the plunger, so that the effect of eliminating lateral force is achieved.

Description

Technical Field

[0001] This invention relates to the field of piston pump technology, and in particular to a discrete cylinder swashplate piston pump. Background Technology

[0002] Axial piston pumps are evolving towards larger displacement, ultra-high pressure, and wider speed ranges. However, in common piston pumps operating under ultra-high pressure and high speed conditions, the increased specific pressure and specific work between the slipper and the swashplate lead to slipper wear and lubrication failure. Furthermore, in large-displacement swashplate piston pumps, the increased diameter of the piston distribution circle and the increased slipper circumference cause uneven temperature rise inside and outside the slipper's oil film, resulting in slipper deflection and accelerated wear due to direct contact between the slipper and the swashplate, thus reducing pump performance. At high speeds, the increased inertial torque of the rotating components makes them prone to overturning. Common axial piston pumps with rotating cylinder blocks or swashplate designs require stress on the rotating components. Torque imbalance increases the size of the plunger pump and the design difficulty of the cylinder spline; at the same time, it leads to an increase in the lateral force on the plunger, and the lateral force is irregular, resulting in unstable plunger pair seals, increased leakage, and difficulty in establishing a stable plunger pair oil film, which has a detrimental effect on plunger lubrication and life; at extremely low speeds, the hydrodynamic effect of the plunger pair oil film and the slipper pair oil film is difficult to establish, and the lateral force causes dry friction between the plunger and the cylinder, making the slipper prone to burning and metal peeling, which in turn affects the cleanliness of the oil and affects the entire plunger pump and even the hydraulic system. Summary of the Invention

[0003] This invention provides a discrete cylinder swashplate piston pump, which addresses the issues of slipper wear and failure, large rotational inertia leading to overturning of the cylinder assembly, and irregular lateral forces on the pistons through optimized design. It replaces several slippers with an integral floating disc, and the discrete cylinder body is a cylindrical piston with a ball head. The ball head can be hinged to the distribution end cap, and its cylindrical hole can mate with a fine piston assembly. The swashplate design, employing dynamic pressure support to balance the overturning moment, reduces pump volume, and utilizes a central universal joint for positioning. This novel structural design improves the pump's speed range, low-speed stability, working pressure, and power density ratio.

[0004] To achieve the above objectives, the present invention provides a swashplate piston pump drive mechanism, comprising a swashplate, a floating plate, a movable floating pressure plate, and a fixed floating pressure plate arranged sequentially. The swashplate is driven and connected to a main shaft. The swashplate has an inclined mounting surface. The floating plate is mounted on the inclined mounting surface and is fixedly connected to the movable floating pressure plate. The floating plate and the movable floating pressure plate are respectively hinged to the ball head of the fine piston and the ball head of the discrete cylinder. A sealing groove adapted to the ball head of the fine piston is formed on the connection surface between the floating plate and the movable floating pressure plate. The movable floating pressure plate is in real-time contact with the inclined mounting surface of the swashplate.

[0005] The fixed floating pressure plate is in a vertical state and is hinged to the discrete cylinder body. The thin plunger can reciprocate along the axis of the thick plunger.

[0006] The fixed floating pressure plate and the movable floating pressure plate are movably connected by a central universal joint, and the axis of the central universal joint on the fixed floating pressure plate is located on the rotation axis of the main shaft.

[0007] Preferably, a high-pressure oil groove is provided on the circumferential surface of the swashplate.

[0008] Preferably, the thin plungers are uniformly distributed in a ring along the center of the floating disc and the movable floating pressure plate; the discrete cylinder body is uniformly distributed in a ring along the center of the distribution end cover and the fixed floating pressure plate.

[0009] Preferably, both the discrete cylinder and the fine plunger include a plunger rod and a plunger ball head connected together. The plunger rod of the discrete cylinder has a plunger cavity, and the plunger rod of the fine plunger can be inserted into the plunger cavity to make axial movements.

[0010] Preferably, the plunger ball head is provided with an annular hydrostatic support band.

[0011] Preferably, the inclined surface of the swash plate is provided with an oil passage groove to connect all plunger oil ports on the high-pressure side and the low-pressure side, and a high-pressure oil groove is provided on the circumferential surface of the swash plate to connect with the high-pressure oil groove on the inclined surface to balance the lateral force. The high-pressure oil groove has holes drilled to the end face of the swash plate for hydrostatic support.

[0012] The present invention also provides a discrete cylinder block swashplate type rotary swashplate piston pump using the above-described swashplate piston pump drive mechanism, comprising a housing, a distribution end cover and a rear end cover fixedly connected, wherein the housing has an installation space, and a swashplate, a floating plate, a movable floating pressure plate and a fixed floating pressure plate are sequentially installed in the installation space, the swashplate is driven connected to the main shaft, and both the main shaft and the swashplate are rotatably connected to the housing;

[0013] The distribution end cover has a vertical mounting surface, and a fixed floating pressure plate is coaxially arranged on the vertical mounting surface. Both the distribution end cover and the fixed floating pressure plate are hinged to the ball head of the discrete cylinder body. A sealing groove adapted to the ball head of the coarse plunger is opened on the connection surface between the distribution end cover and the fixed floating pressure plate.

[0014] The distribution end cover is provided with a one-way valve and a screw plug. The one-way valve is installed at the oil inlet and outlet of the distribution end cover, and the screw plug separates the high and low pressure oil chambers.

[0015] Preferably, a wear-resistant disc is provided between the end face of the swash plate and the housing, and the wear-resistant disc is connected to the housing by a locating pin; a sliding bushing is provided between the circumferential surface of the swash plate and the housing.

[0016] Preferably, the swash plate includes a cylindrical section and an inclined section connected together. The cylindrical section is coaxially connected to the main shaft via a spline and is axially positioned by a retaining ring. The outer circle of the cylindrical section is rotatably connected to the housing via a sliding bearing.

[0017] The present invention achieves the following beneficial effects compared to the prior art:

[0018] This invention employs a floating disc design, eliminating the single slipper in traditional plunger pumps, with all plungers mounted on the floating disc. The larger mating surface between the floating disc and the swashplate results in a more stable oil film. Furthermore, the use of an integral sealing strip ensures stable sliding speed of the inner and outer sealing strips on the swashplate. The consistent temperature rise of the oil due to shear force and pressure difference prevents slipper deflection caused by different oil temperature rises, thus enhancing anti-overturning capability.

[0019] This invention employs a swashplate design, but innovates the method for balancing the lateral torque of the swashplate. First, a bushing engages with the circumferential surface of the swashplate, utilizing the dynamic pressure support generated by the wedge-shaped space formed by the swashplate's circumferential surface and the bushing. Second, a small groove with a calculated area is cut into the circumferential surface, through which high-pressure oil flows. This balances the lateral torque generated during the swashplate's rotation, eliminating the need for bearings to balance the rotating components and significantly reducing the pump's size.

[0020] In this invention, the distance between the two plunger ball heads changes periodically with the oscillation of the floating disc, and the volume formed by each pair of plungers and the discrete cylinder also changes regularly. By discretizing the cylinder, the weight is greatly reduced. Since the plungers do not revolve around the axis and the three rotational degrees of freedom of the plunger ball joint on the floating disc are not restricted, the ball joint plunger is not subject to lateral forces, the friction between the fit is greatly reduced, a stable plunger auxiliary oil film can be formed, and the leakage is also reduced. The flow distribution adopts valve flow distribution.

[0021] In this invention, a central universal joint is used to limit the relative position between the two floating pressure plates. Since the universal joint can rotate without changing the relative position of the two components, it can achieve a good positioning effect. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 A schematic diagram of the overall structure of a discrete cylinder swashplate type rotary swashplate piston pump provided by the present invention;

[0024] Figure 2 A schematic diagram of the swashplate structure (I);

[0025] Figure 3 Schematic diagram of swashplate structure (II);

[0026] Figure 4 This is a schematic diagram of the structure of the fine plunger, discrete cylinder block, and central universal joint. Detailed Implementation

[0027] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0028] like Figures 1 to 4 As shown, the discrete cylinder swashplate piston pump provided in this embodiment includes a main shaft 1, a housing 2, a swashplate 4, a floating disc universal joint assembly, a fine piston 8, a discrete cylinder 9, a distribution end cover 11, and a rear end cover 14. The housing 2 serves as the carrier for the main load-bearing components, on which the main shaft 1, wear-resistant disc 6, and sliding bushing 5 are mounted. These components are connected to the distribution end cover 11 and the rear end cover 14 with screws, forming the external enclosure of the pump. The main shaft 1 transmits the torque generated by the motor, which is then transmitted to the swashplate 4 via a spline connection. The swashplate 4 rotates, causing the floating disc 6 to oscillate periodically, thereby compressing the piston and generating a variable volume.

[0029] In addition to being connected to the spindle 1 via a spline, the swashplate 4 has two other important matings. The first is the mating with the wear-resistant disc 3. The bottom plane of the swashplate 4 has hydrostatic support grooves and support bands, which reduce the pressure impact of high-pressure oil on the mating surfaces and further improve the lubrication performance. The second is the mating between the circumferential surface of the swashplate 4 and the sliding bushing 5, which restricts the radial displacement of the swashplate 4. The dynamic pressure effect generated between the swashplate 4 and the sliding bushing 5, together with the high-pressure oil grooves on the circumferential surface of the swashplate 4, balances the lateral torque experienced by the swashplate during rotation.

[0030] The floating disc assembly includes a floating disc 6 and a movable floating pressure plate 7; a thin plunger 8 is placed between the floating disc 6 and the movable floating pressure plate 7, and the movable floating pressure plate 7 is fastened to the floating disc 6 by screws to fix the ball head of the thin plunger 8. Another fixed floating pressure plate 10 fixes the ball head of the discrete cylinder block 9 to the distribution end cover 11 and is fastened to the distribution end cover 11 with bolts.

[0031] The movable floating pressure plate 7 and the fixed floating pressure plate 10 are connected by a central universal joint. Due to the structural characteristics of the universal joint, the relative position of the two floating plate assemblies can be restricted. At the same time, since the universal joint can rotate freely within a certain angular space, it can effectively restrict the relative position between the movable floating pressure plate 7 and the fixed floating pressure plate 10 when the movable floating pressure plate 7 swings.

[0032] Several sets of fine plungers 8 are installed on the movable floating pressure plate 7, which take on the role of traditional sliding shoes.

[0033] The axes of the fine plunger 8 and the discrete cylinder 9 always coincide, and are restricted by the movable floating pressure plate 7 and the fixed floating pressure plate 10 on the floating plate 6 and the distribution end cover 11. This restricts the three translational degrees of freedom of the plunger, but not the three rotational degrees of freedom. Furthermore, the fine plunger 8 will not interfere with or disengage from the discrete cylinder 9 at the two extreme positions. The combination of the fine plunger 8 and the discrete cylinder 9 replaces the original plunger-cylinder fit with a discrete cylinder, forming a closed variable volume.

[0034] The distribution end cover 11 carries several sets of one-way valves 13 responsible for the pump's distribution work. The valve distribution is reliable and efficient, and there is no need to consider the design of the distribution pair. It is also more in line with the distribution work when the plunger does not revolve around the axis. The distribution end cover 11 is provided with screw plugs 12 for separating the high and low pressure oil chambers.

[0035] The floating disc design employed in the above scheme improves the pump's service life and efficiency, and also makes the plunger pump more adaptable to high-pressure and wide-speed range operating conditions. The floating disc supports all the ball joint plungers. During rotation, the contact surface between the slipper and the swashplate changes from a single slipper surface to the entire floating disc. Compared to a single slipper, the force-bearing area is larger, resulting in more stable rotation. It prevents slipper deflection due to different oil temperature rises, largely avoiding overturning and reducing the likelihood of slipper burning. Under high-pressure and high-speed conditions, the oil film establishment is more stable, resulting in better lubrication and reducing the risk of greater wear or leakage.

[0036] The swashplate design employed increases the speed range and reduces the size. In this design, the plunger does not revolve with the spindle; it only expands and contracts within a certain range to create varying volumes, thus eliminating centrifugal force interference and resulting in low rotational inertia. Furthermore, instead of using traditional large bearings to balance the lateral torque of the swashplate rotation, it utilizes the dynamic pressure effect generated by the wedge-shaped space created by the fit between a bushing and the swashplate's circumference, along with a calculated groove on the swashplate's circumference introducing high-pressure oil. These two methods work together to balance the lateral torque generated during swashplate rotation. Compared to traditional swashplate axial piston pumps, this design significantly reduces size, making it suitable for applications with stricter size requirements.

[0037] The plunger assembly used improves rated pressure and low-speed stability. It abandons the traditional plunger-cylinder mating design, using two plungers—one large and one small—with ball ends. The variable volume in the plunger pump is no longer determined by the reciprocating motion of the plungers within the cylinder, but rather by the changing center distance between the two ball ends. At the extreme positions of the ball ends, the two plungers do not interfere or disengage. Because the two plungers only reciprocate and slightly oscillate within a certain range, the stress on the plungers is significantly optimized, and there are no lateral forces, resulting in stable sealing and reduced leakage. Furthermore, the valve-based flow distribution eliminates the need to consider flow distribution pair issues. Compared to traditional swashplate axial plunger pumps, the lateral forces between the plungers and cylinder in the cylinder-plunger assembly are eliminated. This structure improves the stiffness of the plunger pair oil film, solving the problem of difficulty in establishing a stable oil film under high pressure and low speed conditions, reducing plunger wear and leakage. It also provides wide-range operating capability.

[0038] The central universal joint positioning structure is used because the floating disc only oscillates when the swashplate rotates. A structure is needed to ensure that the relative position of the two relatively moving components does not change during the oscillation. Therefore, the central universal joint positioning method is adopted, which can maintain the relative position between the two floating pressure plates without excessively increasing the size of the pump. Moreover, the universal joint technology is relatively mature, easy to maintain, and convenient to design.

[0039] Compared to traditional axial piston pumps, which require two or more bearings to balance the shaft regardless of whether they are through-shaft or through-shaft types, the piston pump provided by this invention eliminates the cylinder block and directly machines the position for placing the piston on the end cover and fixes it with a pressure plate, saving internal pump space and simplifying the design process.

[0040] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A discrete cylinder block swashplate type rotary swashplate piston pump, characterized in that, The device includes a swashplate piston pump drive mechanism and a fixedly connected housing. The swashplate piston pump drive mechanism includes a swashplate, a floating plate, a movable floating pressure plate, and a fixed floating pressure plate arranged in sequence. The swashplate is driven and connected to a main shaft. The swashplate has an inclined mounting surface. The floating plate is mounted on the inclined mounting surface and is fixedly connected to the movable floating pressure plate. The floating plate and the fixed floating pressure plate are respectively hinged to the ball head of the fine piston and the ball head of the discrete cylinder. A sealing groove adapted to the ball head of the fine piston is opened on the connection surface between the floating plate and the movable floating pressure plate. The floating plate is in real-time contact with the inclined mounting surface of the swashplate. The fixed floating pressure plate is in a vertical position, and the thin plunger can reciprocate along the axis of the discrete cylinder body; The fixed floating pressure plate and the movable floating pressure plate are movably connected by a central universal joint, and the axis of the central universal joint on the fixed floating pressure plate is located on the rotation axis of the main shaft; The inclined surface of the swash plate is provided with an oil passage groove to connect all the plunger oil ports on the high-pressure side and the low-pressure side. The circumferential surface of the swash plate is provided with a high-pressure oil groove that is connected to the oil passage groove on the inclined surface to balance the lateral force. The high-pressure oil groove has holes drilled to the end face of the swash plate for hydrostatic support. The housing has an installation space, and a swashplate piston pump drive mechanism is installed in the installation space. The main shaft and the swashplate are both rotatably connected to the housing. A wear-resistant disc is provided between the end face of the swash plate and the housing, and the wear-resistant disc is connected to the housing by a locating pin; a sliding bushing is provided between the circumferential surface of the swash plate and the housing.

2. The discrete cylinder swashplate type rotary swashplate piston pump according to claim 1, characterized in that, The fine plungers are evenly distributed in a ring along the center of the floating disk and the movable floating pressure plate; the discrete cylinder body is evenly distributed in a ring along the center of the distribution end cover and the fixed floating pressure plate.

3. The discrete cylinder swashplate type rotary swashplate piston pump according to claim 1, characterized in that, Both the discrete cylinder and the fine plunger include a plunger rod and a plunger ball head connected together. The plunger rod of the discrete cylinder has a plunger cavity, and the plunger rod of the fine plunger can be inserted into the plunger cavity to move axially.

4. The discrete cylinder swashplate type rotary swashplate piston pump according to claim 1, characterized in that, The bottom plane of the swashplate is provided with an annular hydrostatic support band.

5. The discrete cylinder block swashplate piston pump according to claim 1, characterized in that, It also includes a distribution end cover and a rear end cover. The distribution end cover has a vertical mounting surface. A fixed floating pressure plate is coaxially arranged on the vertical mounting surface. Both the distribution end cover and the fixed floating pressure plate are hinged to the ball head of the discrete cylinder body. A sealing groove adapted to the ball head of the discrete cylinder body is opened on the connection surface between the distribution end cover and the fixed floating pressure plate. The distribution end cover is provided with a one-way valve and a screw plug. The one-way valve is installed at the oil inlet and outlet of the distribution end cover, and the screw plug separates the high and low pressure oil chambers.

6. The discrete cylinder swashplate type rotary swashplate piston pump according to claim 5, characterized in that: The swash plate includes a cylindrical section and an inclined section connected together. The cylindrical section is coaxially connected to the main shaft via a spline and is axially positioned by a retaining ring. The outer circle of the cylindrical section is rotatably connected to the housing via a sliding bushing.

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