A constant power controlled hydraulic single cylinder dual variable piston pump

Abstract

The present invention discloses a constant power controlled hydraulic single cylinder dual variable plunger pump, comprising a pump housing, a cylinder body, and a transmission shaft. The cylinder body is processed with an assembly hole and a plurality of plunger cavities surrounding the assembly hole and equipped with plungers. A swash plate and a variable support column matched with the top surface support of the swash plate are arranged in the pump housing. A lever body is formed by extending one end of the swash plate. A variable spring elastically connected to the lever body is installed below the lever body in the pump housing. The variable spring uses spring force to use the variable support column as a fulcrum of the lever to push the swash plate to flip upward to increase the inclination angle of the swash plate. The plunger in the oil pressure area pushes the swash plate to overcome the spring force by the hydraulic force, so that the swash plate automatically matches the inclination angle under the joint action of the spring force and the hydraulic force when the load pressure changes to realize the constant power control of the pump. The present invention has a small size, low cost, and compact structure. It can automatically adjust the inclination angle of the swash plate by the interaction of the spring force and the hydraulic force, thereby realizing the constant power control of the pump.

Description

Technical Field

[0001] The invention relates to the technical field of hydraulic control, in particular to a single-cylinder dual-variable plunger pump with constant power control performance, specifically a constant power controlled hydraulic single-cylinder dual-variable plunger pump. Background Art

[0002] Hydraulic double plunger pumps are widely used in excavators, but conventional double pumps are mechanically connected axially with a long axial distance, which is not conducive to the use of compact installation space in micro excavators. Therefore, the pumps generally used in micro excavators are compact double variable pumps. There are two pumps installed back to back, and there are also axially parallel installations. However, the control method is to use a special pump control valve to control the total power variable. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a constant power controlled hydraulic single-cylinder dual variable piston pump which is small in size, low in cost, compact in structure and can realize constant power control without a pump control valve in view of the status quo of the above-mentioned prior art.

[0004] The technical solution adopted by the present invention to solve the above technical problems is:

[0005] A constant power controlled hydraulic single-cylinder dual-variable plunger pump comprises a cylinder body arranged in a pump casing and a transmission shaft for driving the cylinder body to rotate, the cylinder body is processed with an assembly hole for the transmission shaft to pass through and assemble and a plurality of plunger cavities with plungers installed therein surrounding the assembly hole, a slanted plate is obliquely arranged in the pump casing to enable the plunger to suck and discharge oil; a variable support column matched with a top surface rotation support of the slanted plate is arranged in the pump casing, a lever body is extended to be formed at one end of the slanted plate, a variable spring elastically connected to the lever body is installed below the lever body in the pump casing, the variable spring uses spring force to use the variable support column as a fulcrum of the lever to push the slanted plate to flip upward to increase the inclination angle of the slanted plate, and the plunger in the oil pressure area pushes the slanted plate to overcome the spring force by relying on the hydraulic pressure, so that when the load pressure changes, the slanted plate automatically matches the inclination angle under the joint action of the spring force and the hydraulic force to achieve constant power control of the pump.

[0006] To optimize the above technical solutions, the specific measures taken also include:

[0007] A limiter for limiting the inclination angle of the swash plate is positioned and installed on the top wall inside the above-mentioned pump housing, and the limiter includes a left limiter located on the left side of the variable support column and a right limiter located on the right side of the variable support column; the left limiter cooperates with the top surface of the left end of the swash plate to limit the minimum inclination angle of the swash plate, and the right limiter cooperates with the top surface of the lever body to limit the maximum inclination angle of the swash plate.

[0008] The variable support column is a cylinder, and the lever fulcrum of the swash plate and the indexing center of the plunger are eccentrically arranged to form a distance δ for realizing torque offset.

[0009] The center of the swash plate is processed with an elongated hole for the transmission shaft to pass through, and the top surface of the swash plate is processed with coaxial arc-shaped positioning grooves on both sides of the elongated hole, and the variable support column anti-slip positioning is arranged in the positioning groove.

[0010] The above-mentioned pump casing is assembled from an upper casing and a bottom cover; a spring top seat is installed on the top of the variable spring, and the top surface of the spring top seat is formed with a top seat ball head that cooperates with the top of the lever body, and the bottom surface of the lever body is formed with an arc-shaped ball bowl that cooperates with the top seat ball head of the spring top seat, and a spring base is pressed against the bottom end of the variable spring.

[0011] A pressure regulating screw hole is formed on the above-mentioned bottom cover, in which a pressure regulating bolt is spirally installed for adjusting the preload pressure of the variable spring by pressing the spring base, and the pressure regulating bolt is spirally equipped with a locking nut that presses against the bottom cover to lock the pressure regulating bolt.

[0012] The cylinder body is formed with ten plunger cavities for installing plungers around the assembly hole. The top of the plunger is slidably connected with the bottom of the inclined plate through the sliding shoe of the hinge. An internal rack is formed in the assembly hole to match the tooth groove on the transmission shaft.

[0013] The bottom surface of the cylinder body is provided with an oil distribution plate for distributing oil for the plunger to suck and discharge oil. The oil distribution plate is provided with an arc-shaped oil suction window and a waist-shaped oil pressure window. The oil pressure window includes a first oil pressure window on the outer arc and a second oil pressure window on the inner arc.

[0014] The bottom surface of the cylinder body is formed with a waist-shaped oil port connected to the corresponding plunger cavity. The waist-shaped oil port includes a first waist-shaped oil port on the outer circumference and a second waist-shaped oil port on the inner circumference. The first waist-shaped oil port and the second waist-shaped oil port are arranged alternately.

[0015] A preload spring is installed in the assembly hole of the cylinder body on the transmission shaft to maintain a certain pressure between the cylinder body and the oil distribution plate. The upper end of the preload spring presses on the spring retaining ring of the transmission shaft, and the lower end of the preload spring is connected to the hole in the cylinder body assembly hole through a gasket and a retaining ring.

[0016] Compared with the prior art, the present invention is provided with a variable support column as a fulcrum of the swash plate lever in the housing, so that the swash plate can be turned over with the variable support column as the fulcrum to change the inclination angle of the swash plate. The larger the inclination angle of the swash plate, the larger the effective stroke of the plunger, and the larger the displacement of the pump, and vice versa. The present invention is provided with a variable spring below the end of the swash plate with the lever body, so that when the load is small, the variable spring can use the spring force to push the swash plate to the maximum angle position. When the external load gradually increases, the liquid pressure in the oil pressure area will generate a combined torque on the swash plate through the plunger to counteract the spring torque of the variable spring until the torque balance point is reached and the inclination angle of the swash plate tends to be stable. The single-cylinder dual-variable plunger pump of the present invention uses liquid pressure at one end and spring force at the other end. By overcoming the spring force, the force is kept balanced to achieve automatic matching of the swash plate pressure angle, that is, the inclination angle. The higher the pressure, the smaller the angle, and the smaller the displacement, achieving approximate constant power control.

[0017] The invention has small volume, low cost and compact structure, and can automatically adjust the inclination angle of the swash plate by utilizing the interaction between spring force and hydraulic force, thereby realizing constant power control of the pump. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the structure of the present invention;

[0019] Figure 2 It is a schematic diagram of the three-dimensional structure of the variable support column of the present invention;

[0020] Figure 3 It is a three-dimensional structural schematic diagram of the swash plate of the present invention;

[0021] Figure 4 It is a three-dimensional structural schematic diagram of a swash plate with a variable support column installed in the present invention;

[0022] Figure 5 It is a structural schematic diagram of the top surface of the cylinder body of the present invention;

[0023] Figure 6 It is a structural schematic diagram of the bottom surface of the cylinder body of the present invention;

[0024] Figure 7 It is a structural schematic diagram of the oil distribution plate of the present invention;

[0025] Figure 8 Schematic diagram of the position of moment offset of the present invention; the position defined by the dotted line in the figure is the position where the variable support column is installed;

[0026] Fig. 9 It is a principle diagram of the lever for realizing constant power according to the present invention. DETAILED DESCRIPTION

[0027] The embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings.

[0028] Figures 1 to 9 It is a structural schematic diagram of the present invention.

[0029] The figures are marked as follows: preload spring H, first waist-shaped oil port K1, second waist-shaped oil port K2, oil distribution plate P, oil suction window P1, first oil pressure window P2, second oil pressure window P3, slipper X, pump housing 1, upper housing 11, bottom cover 12, cylinder body 2, assembly hole 2a, plunger cavity 2b, inner rack 2c, transmission shaft 3, plunger 4, inclined plate 5, elongated hole 5a, positioning groove 5b, lever body 51, variable support column 6, variable spring 7, spring top seat 71, top seat ball head 71a, spring base 72, left limiter 81, right limiter 82, pressure regulating bolt 9, locking nut 91.

[0030] As shown in the figure, the present invention discloses a constant power control hydraulic single cylinder dual variable piston pump, comprising a cylinder body 2 arranged in a pump housing 1 and a transmission shaft 3 for driving the cylinder body 2 to rotate. Both ends of the transmission shaft 3 are rotatably supported in the pump housing 1 through bearings, and the center of the cylinder body 2 is processed with an assembly hole 2a for the transmission shaft 3 to pass through and assemble, and a plurality of plunger cavities 2b surrounding the assembly hole 2a and equipped with plungers 4. Figure 5 and Figure 6 As shown, an inner rack 2c is formed in the assembly hole 2a of the cylinder body 2, and a tooth groove meshing with the inner rack 2c in the assembly hole 2a is formed on the outer peripheral surface of the transmission shaft 3. In this way, the transmission shaft 3 can drive the cylinder body 2 to rotate together through the cooperation of the tooth groove and the inner rack 2c, thereby driving the plunger 4 installed in the plunger cavity 2b to rotate together with the cylinder body 2. A swash plate 5 is obliquely arranged in the pump housing 1. The plunger 4 is pushed and pulled by the swash plate 5 in the sliding contact with the swash plate 5, and reciprocates in the plunger cavity 2b, thereby realizing the suction and discharge of oil by the plunger 4. Figure 1As shown, the key point of the present invention is that a variable support column 6 is provided in the pump housing 1 to match the top surface rotation support of the swash plate 5. The variable support column 6 is a cylindrical structure made of metal material. A lever body 51 is formed on one end of the swash plate 5. A variable spring 7 elastically connected to the lever body 51 is installed below the lever body 51 in the pump housing 1. The variable spring 7 can use its own spring force to use the variable support column 6 as the lever fulcrum of the swash plate 5 to push the swash plate 5 to flip upward, thereby increasing the inclination angle of the swash plate 5. When the load of the pump is small, the spring force of the variable spring 7 can push the swash plate 5 to the maximum angle position, at which time the displacement of the pump is the largest. On the contrary, when the angle of the swash plate 5 decreases, the displacement of the pump also decreases, because the change in the inclination angle of the swash plate 5 can change the effective stroke of the plunger 4. The plunger 4 realizes oil suction and discharge by reciprocating motion. The area where the plunger 4 is in the oil suction state is called the oil suction area, and the area where the plunger 4 pressurizes and discharges the sucked oil is called the oil pressure area. The key to achieving constant power control of the pump in the present invention is to use the plunger 4 in the oil pressure area to rely on the hydraulic pressure to push the swash plate 5 to overcome the spring force, so that the swash plate 5 automatically matches the inclination angle under the combined action of the spring force and the hydraulic force when the load pressure changes to achieve constant power control of the pump. That is to say, when the external load gradually increases, the hydraulic pressure in the lower half of the plunger in the oil pressure area realizes a combined torque on the swash plate 5 to counteract the spring torque until the torque balance point is reached and the swash plate 5 tends to be stable. The present invention adopts a method in which one end is hydraulic pressure and the other end is spring force. By overcoming the spring force, the force is kept balanced to achieve automatic matching of the inclination angle of the swash plate 5. The higher the hydraulic pressure, the smaller the angle of the swash plate 5 and the smaller the displacement, thereby achieving near constant power control of the pump.

[0031] In the embodiment, a limiter for limiting the inclination angle of the swash plate 5 is positioned and installed on the top wall of the pump housing 1. The limiter is used to prevent the inclination angle of the swash plate 5 from being too large or too small. When the swash plate 5 is parallel to the top surface of the cylinder body 2, the stroke of the plunger 4 will be zero, so it is impossible to suck and discharge oil. When the inclination angle of the swash plate 5 exceeds a certain range, the plunger 5 is also prone to pull the cylinder and damage. The limiter of the present invention includes a left limiter 81 located on the left side of the variable support column 6 and a right limiter 82 located on the right side of the variable support column 6; the left limiter 81 cooperates with the top surface of the left end of the swash plate 5 to limit the minimum inclination angle of the swash plate 5, and the right limiter 82 cooperates with the top surface of the lever body 51 to limit the maximum inclination angle of the swash plate 5.

[0032] In the embodiment Figure 8 and Fig. 9 As shown in the figure, the lever fulcrum of the swash plate 5 and the indexing center of the plunger 4 of the present invention are eccentrically arranged to form a distance δ for realizing torque offset. The eccentric distance δ between the lever fulcrum of the swash plate 5 and the indexing center of the plunger 4 is offset in the direction of the lever body 51. Fig. 9It can be seen that the distance between the action point of the variable spring 7G and the swash plate 5 and the indexing center of the plunger 4 is LT, and the distance between the plunger 4 and the indexing center of the plunger 4 is L. In the figure, Ft represents the spring force, and Fp represents the hydraulic pressure.

[0033] In the embodiment, the center of the swash plate 5 of the present invention is processed with an elongated hole 5a for the transmission shaft 3 to pass through, and the top surface of the swash plate 5 is processed with coaxial arc-shaped positioning grooves 5b on both sides of the elongated hole 5a, and the variable support column 6 is anti-slipping and positioned in the positioning grooves 5b. The positioning grooves 5b can prevent the variable support column 6 from rolling left and right and slipping out of the designed support point.

[0034] In the embodiment, the pump housing 1 of the present invention is composed of an upper housing 11 and a bottom cover 12. A spring top seat 71 is installed at the top of the variable spring 7, and a top seat ball head 71a that is matched with the lever body 51 is formed on the top surface of the spring top seat 71, and an arc-shaped ball bowl that matches the top seat ball head 71a of the spring top seat 71 is formed on the bottom surface of the lever body 51, and the top seat ball head 71a can rotate within the range limited by the arc-shaped ball bowl, and a spring base 72 is also pressed against the bottom end of the variable spring 7.

[0035] In the embodiment, a pressure-adjusting screw hole is formed on the bottom cover 12 of the present invention, in which a pressure-adjusting bolt 9 is spirally installed for adjusting the preload pressure of the variable spring 7 by pressing the spring base 72, and the pressure-adjusting bolt 9 is spirally equipped with a locking nut 91 for pressing and locking the pressure-adjusting bolt 9 against the bottom cover 12.

[0036] like Figure 5 , Figure 6 and Figure 1 As shown, the cylinder body 2 of the present invention is formed with ten plunger cavities 2b for installing the plunger 4 around the assembly hole 2a. The top of the plunger 4 is slidably connected with the bottom surface of the swash plate 5 through the sliding shoe X of the hinge.

[0037] In the embodiment, the bottom surface of the cylinder body 2 of the present invention is provided with an oil distribution plate P for distributing oil for the plunger to suck and discharge oil. The oil distribution plate P is provided with an arc-shaped oil suction window P1 and a waist-shaped oil pressure window. The oil pressure window includes a first oil pressure window P2 on the outer arc and a second oil pressure window P3 on the inner arc.

[0038] The bottom surface of the cylinder body 2 is formed with a waist-shaped oil port connected to the corresponding plunger cavity 2b, and the waist-shaped oil port includes a first waist-shaped oil port K1 on the outer circumference and a second waist-shaped oil port K2 on the inner circumference. The first waist-shaped oil port K1 and the second waist-shaped oil port K2 are arranged alternately.

[0039] A preload spring H is installed on the transmission shaft 3 in the assembly hole 2a of the cylinder body 2 to maintain a certain pressure between the cylinder body 2 and the oil distribution plate P. The upper end of the preload spring H presses on the spring retaining ring of the transmission shaft 3, and the lower end of the preload spring H is connected to the hole in the assembly hole 2a of the cylinder body 2 through a gasket and a retaining ring.

[0040] The best embodiment of the present invention has been described, and various changes or modifications made by those skilled in the art will not depart from the scope of the present invention.

Claims

1. A constant power controlled hydraulic single cylinder dual variable piston pump, comprising a cylinder body (2) arranged in a pump housing (1) and a transmission shaft (3) for driving the cylinder body (2) to rotate, the cylinder body (2) being processed with an assembly hole (2a) for the transmission shaft (3) to pass through and assemble, and a plurality of plunger cavities (2b) surrounding the assembly hole (2a) and equipped with plungers (4), and a slant plate (5) is obliquely arranged in the pump housing (1) to enable the plunger (4) to achieve oil suction and discharge; its characteristics are: The pump housing (1) is provided with a variable support column (6) which cooperates with the top surface rotation support of the swash plate (5); one end of the swash plate (5) is extended to form a lever body (51); a variable spring (7) which elastically top-connects the lever body (51) is installed in the pump housing (1) below the lever body (51); the variable spring (7) uses spring force to use the variable support column (6) as the lever fulcrum of the swash plate (5) to push the swash plate (5) to flip upward to increase the inclination angle of the swash plate (5); the plunger (4) in the oil pressure area pushes the swash plate (5) to overcome the spring force by relying on the hydraulic pressure, so that the swash plate (5) automatically matches the inclination angle under the combined action of the spring force and the hydraulic pressure when the load pressure changes to achieve constant power control of the pump; A limiter for limiting the inclination angle of the swash plate (5) is positioned and installed on the top wall of the pump housing (1), and the limiter comprises a left limiter (81) located on the left side of the variable support column (6) and a right limiter (82) located on the right side of the variable support column (6); the left limiter (81) cooperates with the top surface of the left end of the swash plate (5) to limit the minimum inclination angle of the swash plate (5), and the right limiter (82) cooperates with the top surface of the lever body (51) to limit the maximum inclination angle of the swash plate (5); The variable support column (6) is a cylinder, and the lever fulcrum of the swash plate (5) and the indexing center of the plunger (4) are eccentrically arranged to form a distance δ for realizing torque offset; The center of the swash plate (5) is processed with an elongated hole (5a) for the transmission shaft (3) to pass through, and the top surface of the swash plate (5) is processed with coaxial arc-shaped positioning grooves (5b) on both sides of the elongated hole (5a), and the variable support column (6) is arranged in the positioning groove (5b) for anti-dropping positioning; The pump housing (1) is composed of an upper housing (11) and a bottom cover (12) assembled together; a spring top seat (71) is installed at the top of the variable spring (7); a top seat ball head (71a) is formed on the top surface of the spring top seat (71) and is matched with the lever body (51); an arc-shaped ball bowl is formed on the bottom surface of the lever body (51) and is matched with the top seat ball head (71a) of the spring top seat (71); and a spring base (72) is pressed against the bottom end of the variable spring (7); The bottom surface of the cylinder body (2) is provided with an oil distribution plate (P) for distributing oil for the plunger to suck and discharge oil. The oil distribution plate (P) is provided with an arc-shaped oil suction window (P1) and a waist-shaped oil pressure window. The oil pressure window comprises a first oil pressure window (P2) on the outer arc and a second oil pressure window (P3) on the inner arc.

2. A constant power controlled hydraulic single cylinder dual variable piston pump according to claim 1, characterized in that: The bottom cover (12) is formed with a pressure regulating screw hole, in which a pressure regulating bolt (9) is spirally installed for adjusting the pre-tightening pressure of the variable spring (7) by pressing the spring base (72), and the pressure regulating bolt (9) is spirally equipped with a locking nut (91) for pressing the bottom cover (12) to lock the pressure regulating bolt (9).

3. A constant power controlled hydraulic single cylinder dual variable piston pump according to claim 2, characterized in that: The cylinder body (2) is formed with ten plunger cavities (2b) for installing the plunger (4) around the assembly hole (2a); the top end of the plunger (4) is slidably connected with the bottom surface of the inclined plate (5) through a hinged sliding shoe (X); and the assembly hole (2a) is formed with an internal rack (2c) that matches the tooth groove on the transmission shaft (3).

4. A constant power controlled hydraulic single cylinder dual variable piston pump according to claim 3, characterized in that: The bottom surface of the cylinder body (2) is formed with a waist-shaped oil port connected to the corresponding plunger cavity (2b), and the waist-shaped oil port includes a first waist-shaped oil port (K1) on the outer circumference and a second waist-shaped oil port (K2) on the inner circumference. The first waist-shaped oil port (K1) and the second waist-shaped oil port (K2) are arranged in an alternating manner.

5. A constant power controlled hydraulic single cylinder dual variable piston pump according to claim 4, characterized in that: A preload spring (H) for maintaining a certain pressure between the cylinder body (2) and the oil distribution plate (P) is installed in the assembly hole (2a) of the cylinder body (2) on the transmission shaft (3). The upper end of the preload spring (H) presses against the spring retaining ring of the transmission shaft (3), and the lower end of the preload spring (H) is connected to the hole in the assembly hole (2a) of the cylinder body (2) through a gasket and a retaining ring.

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