A hydraulic dual cylinder two-stage plunger pump and a hydraulic tool

Abstract

This invention provides a hydraulic dual-cylinder, dual-stage piston pump and a hydraulic tool. The hydraulic dual-cylinder, dual-stage piston pump includes a cylinder body, a primary piston, a secondary piston, a primary check valve, and a secondary check valve. The cylinder body forms a piston chamber and has an oil inlet and an oil outlet. The secondary piston is slidably mounted in the piston chamber. The upper end face of the primary piston mates with the piston chamber to form a primary oil chamber, which communicates with the oil inlet. The secondary piston has a secondary piston section, which is slidably mounted in the piston chamber and located on the side of the primary piston away from the primary oil chamber. The piston chamber forms a secondary oil chamber between the secondary piston section and the primary piston. The lower end face of the secondary piston section, away from the secondary oil chamber, mates with the piston chamber to form a tertiary oil chamber, which communicates with the oil outlet. The primary check valve is located on the primary piston, and the secondary check valve is located on the secondary piston section. This design enables efficient and stable operation under load, while also improving working efficiency under no-load conditions.

Description

Technical Field

[0001] This invention relates to the field of hydraulic tool technology, and in particular to a hydraulic dual-cylinder dual-stage piston pump and a hydraulic tool. Background Technology

[0002] Most existing hydraulic tools employ single-cylinder piston pumps with a cam and spring mechanism. The pump uses a cam to push the piston, which compresses the hydraulic oil while simultaneously squeezing the spring, creating high-pressure oil that drives hydraulic actuators (e.g., cylinders or motors). The spring then pushes the piston back to its original position, achieving reciprocating motion. In this type of pump, half of the stroke is the spring return stroke, which does no work. This, combined with the other half of the stroke, creates a significant alternating load in the system, resulting in unstable operation, high vibration, significant impact on the drive unit (e.g., electric motor or gasoline engine), and high energy consumption. Users often desire higher efficiency when using hydraulic tools, but existing tools often operate at the same speed under no-load and load conditions, leading to low actual efficiency. Summary of the Invention

[0003] The purpose of this invention is to provide a hydraulic dual-cylinder dual-stage piston pump and a hydraulic tool, which aims to reduce the alternating load of existing hydraulic tools, improve system stability, and increase working efficiency under no-load conditions.

[0004] To solve the above-mentioned technical problems, embodiments of the present invention provide a hydraulic dual-cylinder two-stage piston pump, comprising:

[0005] A cylinder body, wherein a piston chamber is formed within the cylinder body, and an oil inlet and an oil outlet communicating with the piston chamber are provided on the cylinder wall of the cylinder body;

[0006] A primary piston is slidably mounted in the piston chamber, and the upper end face of the primary piston cooperates with the piston chamber to form a primary oil chamber, which is connected to the oil inlet.

[0007] A secondary plunger has a secondary piston section at one end, which is slidably installed in the piston chamber and located on the side of the primary piston away from the primary oil chamber. The piston chamber forms a secondary oil chamber between the secondary piston section and the primary piston. The lower end face of the secondary piston section away from the secondary oil chamber cooperates with the piston chamber to form a tertiary oil chamber. The tertiary oil chamber is connected to the oil outlet.

[0008] A first-stage check valve is provided on the first-stage piston and is used to open when the force exerted on the first-stage oil chamber is less than the force exerted on the second-stage oil chamber, so as to connect the first-stage oil chamber and the second-stage oil chamber.

[0009] A secondary check valve is provided on the secondary piston section and is used to open when the pressure in the secondary oil chamber is greater than the pressure in the tertiary oil chamber, so as to connect the secondary oil chamber and the tertiary oil chamber.

[0010] Preferably, the first-stage piston comprises:

[0011] A one-way valve sleeve, wherein the one-way valve sleeve is slidably disposed within the piston chamber;

[0012] A one-way valve core is located on the upper side of the one-way valve sleeve. The one-way valve core is movable up and down relative to the one-way valve sleeve. The first-stage one-way valve is disposed between the one-way valve core and the one-way valve sleeve.

[0013] An elastic reset element abuts against the one-way valve core and the inner wall of the piston chamber;

[0014] Specifically, when the one-way valve core abuts against the one-way valve sleeve, the first-stage one-way valve is closed; when the one-way valve core separates from the one-way valve sleeve, the first-stage one-way valve is open.

[0015] Preferably, the primary check valve includes a clearance hole and an oil passage hole that are disposed through the valve sleeve of the check valve, as well as an abutment protrusion and a sealing part disposed on the valve core of the check valve;

[0016] Specifically, when the one-way valve core abuts against the one-way valve sleeve, the abutting protrusion passes downward through the one-way valve sleeve from the clearance hole, and the sealing part blocks the oil passage hole; when the one-way valve core separates from the one-way valve sleeve, the secondary piston part abuts against the lower side of the abutting protrusion, and the sealing part separates from the oil passage hole.

[0017] Preferably, the one-way valve sleeve includes:

[0018] The cylindrical portion is arranged in a cylindrical shape extending vertically, and the cylindrical portion and the inner wall of the piston cavity form a sliding fit in vertically upward.

[0019] A plate-shaped portion is provided at the lower end of the cylindrical portion in a sealing manner, and the plate-shaped portion is provided with the clearance hole and the oil passage hole through it;

[0020] The lower end of the one-way valve core extends into the cylindrical portion, and the abutting protrusion is provided on the lower end surface of the one-way valve core; when the one-way valve core abuts against the one-way valve sleeve, the lower end surface of the one-way valve core abuts against the upper side of the plate-shaped portion; when the one-way valve core separates from the one-way valve sleeve, the lower end surface of the one-way valve core and the plate-shaped portion are arranged vertically at intervals.

[0021] Preferably, a plurality of oil passage holes are provided at intervals along the circumference of the cylindrical portion, and the plurality of oil passage holes are arranged around the clearance hole.

[0022] Preferably, the sealing part is an annular protrusion provided on the peripheral side of the one-way valve core, and the lower surface of the annular protrusion is flush with the lower end face of the one-way valve core.

[0023] Preferably, the lower end of the elastic reset member is sleeved on the upper end of the one-way valve core, the lower end of the elastic reset member abuts against the upper side of the annular protrusion, and the upper end of the elastic reset member abuts against the lower side of the inner wall of the piston chamber.

[0024] Preferably, the clearance hole and the abutment protrusion are in clearance fit; when the one-way valve core abuts against the one-way valve sleeve, the one-way valve core blocks the clearance between the clearance hole and the abutment protrusion.

[0025] Preferably, a bushing is provided in the cylinder body, the bushing is sleeved outside the secondary piston part, the upper side of the bushing, the upper end face of the secondary piston part and the lower end face of the primary piston are fitted together to form the secondary oil chamber, the bushing is sleeved outside the secondary piston part, and the secondary piston part and the bushing form the tertiary oil chamber.

[0026] To achieve the above objectives, the present invention also provides a hydraulic tool, comprising:

[0027] The aforementioned hydraulic dual-cylinder two-stage piston pump;

[0028] The oil tank is connected to the oil inlet of the hydraulic dual-cylinder dual-stage plunger pump;

[0029] The working cylinder is connected to the oil outlet of the hydraulic dual-cylinder two-stage plunger pump;

[0030] The drive unit is connected to the end of the secondary piston of the hydraulic dual-cylinder dual-stage piston pump away from the secondary piston section, and is used to drive the secondary piston section to slide within the piston chamber.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] The hydraulic dual-cylinder dual-stage piston pump of this invention forms a secondary oil chamber and a tertiary oil chamber between the secondary piston and the cylinder body. A secondary check valve is installed on the secondary piston, connecting the secondary and tertiary oil chambers. The secondary check valve opens when the pressure in the secondary oil chamber is greater than the pressure in the tertiary oil chamber, thus forming a dual-cylinder structure. This enables the hydraulic dual-cylinder dual-stage piston pump to perform work throughout its entire stroke, achieving effects such as smoothing alternating loads, reducing vibration, and improving energy utilization efficiency. Furthermore, the hydraulic dual-cylinder dual-stage piston pump is equipped with a primary piston, and a primary check valve is installed on the primary piston to form a dual-stage structure. This dual-stage structure allows for the switching of flow rate between no-load and loaded conditions, thereby improving the pump's working efficiency under no-load conditions. Thus, the hydraulic dual-cylinder dual-stage piston pump combines a dual-cylinder structure and a dual-stage structure, with the two structures linked in structure and function, achieving efficient and stable operation under load while also improving working efficiency under no-load conditions. Attached Figure Description

[0033] One or more embodiments are illustrated by way of example with reference numerals in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements with the same reference numerals in the drawings are denoted as similar elements. Unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0034] Figure 1 This is one of the cross-sectional views of the hydraulic dual-cylinder two-stage piston pump in an embodiment of the present invention;

[0035] Figure 2 for Figure 1 Second sectional view of a medium-pressure hydraulic double-cylinder two-stage piston pump;

[0036] Figure 3 This is a cross-sectional view of the hydraulic tool in an embodiment of the present invention;

[0037] Figure 4 for Figure 3 A magnified view of a section at point A, showing the hydraulic tool in an unloaded state with the secondary plunger at its lowest point;

[0038] Figure 5 for Figure 3 A schematic diagram of the structure after the second-stage plunger moves upward to its highest point;

[0039] Figure 6 for Figure 3 A schematic diagram of a hydraulic tool under load, wherein the secondary plunger is located at the lowest point;

[0040] Figure 7 for Figure 6 A schematic diagram of the structure after the middle and second stage plunger moves upward;

[0041] Figure 8 for Figure 3 One of the hydraulic oil flow diagrams for medium-sized hydraulic tools;

[0042] Figure 9 for Figure 3 Hydraulic oil flow diagram for medium-sized hydraulic tools, part two;

[0043] Figure 10 for Figure 3 Hydraulic oil flow diagram for medium-sized hydraulic tools, Part 3;

[0044] Figure 11 for Figure 3 The fourth hydraulic oil flow diagram for medium-sized hydraulic tools.

[0045] Explanation of reference numerals in the accompanying drawings of this invention:

[0046] Hydraulic tool 1000, hydraulic double-cylinder double-stage piston pump 100, first-stage piston 1, one-way valve sleeve 11, clearance hole 111, oil passage hole 112, cylindrical part 113, plate-shaped part 114, one-way valve core 12, abutment protrusion 121, sealing part 122, annular protrusion 122a, elastic reset element 13, first-stage one-way valve 14, second-stage piston 2, piston oil passage 21, first annular surface 22, installation channel 23, connecting channel 24, annular limiting surface 25, first annular seal 26, second-stage piston part 27, rod part 28, second-stage one-way valve 3. Valve seat 31, oil inlet channel 32, valve ball 33, three-stage oil chamber 4, bushing 5, bushing oil passage 51, second annular surface 52, second annular seal 53, cylinder body 200, piston chamber 210, oil inlet 220, first-stage oil chamber 230, second-stage oil chamber 240, oil outlet 250, suction check valve 260, discharge check valve 270, filter 280, drive device 300, motor 300a, eccentric wheel mechanism 310, push-pull rod 311, eccentric wheel 312, reduction gearbox 320, working cylinder 400, oil tank 500.

[0047] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0048] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0049] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicators will also change accordingly.

[0050] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. If the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0051] To improve the no-load working efficiency of existing hydraulic tools, while reducing operational instability and excessive vibration under load, minimizing the impact of the hydraulic system on the drive unit, and lowering energy consumption, this invention provides a hydraulic dual-cylinder, dual-stage piston pump. This pump can be used in hydraulic tools such as hydraulic pliers. Figure 1 and Figure 2 A preferred embodiment of the hydraulic dual-cylinder two-stage piston pump provided by the present invention is shown. Figures 3 to 11 A preferred embodiment of the hydraulic dual-cylinder two-stage piston pump provided by the present invention is shown for use in hydraulic tools.

[0052] Please see Figures 1 to 4In this embodiment, the hydraulic dual-cylinder dual-stage piston pump 100 includes a cylinder body 200, a primary piston 1, a secondary piston 2, a primary check valve 14, and a secondary check valve 3. A piston chamber 210 is formed within the cylinder body 200. An oil inlet 220 and an oil outlet 250 communicating with the piston chamber 210 are provided on the cylinder wall of the cylinder body 200. The primary piston 1 is slidably mounted within the piston chamber 210, and its upper end face cooperates with the piston chamber 210 to form a primary oil chamber 230, which communicates with the oil inlet 220. One end of the secondary piston 2 is provided with a secondary piston portion 27, which is slidably mounted within the piston chamber 210 and located away from the primary piston 1 and the primary oil chamber 210. On one side of 30, piston chamber 210 forms a secondary oil chamber 240 between secondary piston section 27 and primary piston 1. The lower end face of secondary piston section 27 away from secondary oil chamber 240 cooperates with piston chamber 210 to form tertiary oil chamber 4. Tertiary oil chamber 4 is connected to oil outlet 250. Primary check valve 14 is provided on primary piston 1 and is used to open when the force from primary oil chamber 230 is less than the force from secondary oil chamber 240, so as to connect primary oil chamber 230 and secondary oil chamber 240. Secondary check valve 3 is provided on secondary piston section 27 and is used to open when the pressure in secondary oil chamber 240 is greater than the pressure in tertiary oil chamber 4, so as to connect secondary oil chamber 240 and tertiary oil chamber 4.

[0053] Specifically, the cylinder body 200 may be part of the hydraulic dual-cylinder dual-stage piston pump 100, meaning the hydraulic dual-cylinder dual-stage piston pump 100 includes the cylinder body 200; alternatively, the cylinder body 200 may not be part of the hydraulic dual-cylinder dual-stage piston pump 100, meaning the hydraulic dual-cylinder dual-stage piston pump 100 does not include the cylinder body 200. When the hydraulic dual-cylinder dual-stage piston pump 100 is installed on the hydraulic tool 1000, the cylinder body 200 is formed by a portion of the hydraulic tool 1000 that is independent of the hydraulic dual-cylinder dual-stage piston pump 100. Furthermore, only a portion of the cylinder body 200 may be part of the hydraulic dual-cylinder dual-stage piston pump 100. A portion of the hydraulic dual-cylinder dual-stage piston pump 100, namely the hydraulic dual-cylinder dual-stage piston pump 100, includes a portion of the cylinder body 200. The other portion of the cylinder body 200 and the hydraulic dual-cylinder dual-stage piston pump 100 are two independent parts on the hydraulic tool 1000. When the hydraulic dual-cylinder dual-stage piston pump 100 is installed on the hydraulic tool 1000, the portion of the cylinder body 200 provided on the hydraulic dual-cylinder dual-stage piston pump 100 and the other portion of the cylinder body 200 provided on the hydraulic tool 1000 combine to form a complete cylinder body 200.

[0054] The cylinder wall of cylinder block 200 has an oil inlet 220 and an oil outlet 250 that communicate with piston chamber 210. Please refer to [link / reference]. Figure 3The hydraulic tool 1000 includes an oil tank 500 and a working cylinder 400. The oil tank 500 and the working cylinder 400 are respectively connected to the oil inlet 220 and the oil outlet 250 of the cylinder body 200. When the oil inlet 220 is open, the hydraulic oil in the oil tank 500 can enter the piston chamber 210 of the cylinder body 200 from the oil inlet 220; when the oil outlet 250 is open, the hydraulic oil in the piston chamber 210 of the cylinder body 200 can enter the working cylinder 400 from the oil outlet 250. In this way, the hydraulic oil in the oil tank 500 can enter the piston chamber 210 from the oil inlet 220 and then enter the working cylinder 400 from the oil outlet 250 to drive the piston rod in the working cylinder 400.

[0055] Optionally, please refer to Figures 4 to 7 In this embodiment, an oil suction check valve 260 is provided at the oil inlet 220, and an oil outlet check valve 270 is provided at the oil outlet 250. Thus, the oil suction check valve 260 can control the opening and closing of the oil inlet 220, and similarly, the oil outlet check valve 270 can control the opening and closing of the oil outlet 250. The following description will use the example of an oil inlet 220 and an oil outlet 250 respectively equipped with an oil suction check valve 260 and an oil outlet check valve 270.

[0056] Further, please refer to Figures 4 to 7 In this embodiment, a filter 280 is provided at the oil suction check valve 260. In this way, the hydraulic oil entering the cylinder 200 from the oil inlet 220 can be filtered through the filter 280.

[0057] One end of the piston chamber 210 extends through the cylinder body 200 in its extending direction, while the other end of the piston chamber 210 in its extending direction is sealed. One end of the secondary plunger 2 can be inserted into the piston chamber 210 from the end of the piston chamber 210 that extends through the cylinder body 200. The extending direction of the piston chamber 210 is referred to as the vertical direction, and the end of the piston chamber 210 that extends through the cylinder body 200 is the lower end of the piston chamber 210.

[0058] The oil inlet 220 is connected to the upper end of the piston chamber 210. The first-stage piston 1 is slidably installed in the upper end of the piston chamber 210. The upper end face of the first-stage piston 1 and the piston chamber 210 cooperate to form a first-stage oil chamber 230. The first-stage oil chamber 230 is located between the upper inner wall of the piston chamber 210 and the upper end face of the first-stage piston 1. The first-stage oil chamber 230 is connected to the oil inlet 220. The suction check valve 260 is used to open when the pressure of the first-stage oil chamber 230 is less than the pressure of the oil tank 500 at the other end of the oil inlet 220. Thus, when the suction check valve 260 is open, the hydraulic oil in the oil tank 500 can enter the piston chamber 210 from the oil inlet 220.

[0059] A first-stage check valve 14 is mounted on the first-stage piston 1. The first-stage check valve 14 opens when the force exerted on it from the first-stage oil chamber 230 (i.e., the upper side) is less than the force exerted on it from the second-stage oil chamber 240 (i.e., the lower side), thus connecting the first-stage oil chamber 230 and the second-stage oil chamber 240. The first-stage check valve 14 closes when the force exerted on it from the first-stage oil chamber 230 is not less than the force exerted on it from the second-stage oil chamber 240, thus isolating the first-stage oil chamber 230 and the second-stage oil chamber 240. In this way, the first-stage piston 1 and the first-stage check valve 14 form a two-stage structure of the hydraulic dual-cylinder dual-stage piston pump 100.

[0060] The secondary plunger 2 is axially oriented vertically, and its upper end is slidably disposed within the lower space of the piston chamber 210 located below the primary piston 1. The upper end of the secondary plunger 2 extends into the piston chamber 210 and is provided with a secondary piston portion 27, which is slidably mounted within the piston chamber 210 and located below the primary piston 1. The outer surface of the secondary plunger 2 and the inner wall of the piston chamber 210 enclose a secondary oil chamber 240 and a tertiary oil chamber 4 that are not directly connected. Thus, the secondary plunger 2 forms the secondary oil chamber 240 and the tertiary oil chamber 4 at intervals within the piston chamber 210. The secondary oil chamber 240 is located between the secondary piston portion 27 and the primary piston 1, and is located below the primary oil chamber 230. The lower end face of the secondary piston section 27 cooperates with the piston chamber 210 to form a tertiary oil chamber 4. The tertiary oil chamber 4 is located below the secondary oil chamber 240 and is connected to the oil outlet 250.

[0061] The secondary plunger 2 typically includes a secondary piston portion 27 and a rod portion 28. The rod portion 28 is arranged in a rod shape extending vertically, with its upper end extending into the lower space of the piston chamber 210. The lower end of the rod portion 28 is power-coupled to the drive device 300 of the hydraulic tool 1000, and is used to drive the secondary plunger 2 to reciprocate vertically via the drive device 300. The secondary piston portion 27 is located at the upper end of the rod portion 28, and the diameter of the secondary piston portion 27 is larger than the diameter of the rod portion 28. The drive device 300 can be an electric motor or a gasoline engine, etc. The following description will use an electric motor 300a as an example.

[0062] Optionally, please refer to Figure 3 In this embodiment, the motor 300a is connected to the lower end of the secondary plunger 2 through the eccentric wheel mechanism 310. The motor 300a is used to drive the eccentric wheel mechanism 310 so as to drive the secondary plunger 2 to move up and down through the eccentric wheel mechanism 310.

[0063] Specifically, the eccentric wheel mechanism 310 includes a push-pull rod 311 and an eccentric wheel 312. The push-pull rod 311 is located at the lower end of the secondary plunger 2. The motor 300a is connected to the eccentric wheel 312 through a reduction gearbox 320. When the motor 300a is energized and rotates, it drives the eccentric wheel 312 to rotate through the reduction gearbox 320. The eccentric wheel 312 drives the push-pull rod 311, which in turn pushes the secondary plunger 2 upward. When the motor 300a rotates to 180°, the secondary plunger 2 reaches its highest point, the upward stroke of the secondary plunger 2 ends, and the eccentric wheel 312 begins to pull the secondary plunger 2 downward through the push-pull rod 311.

[0064] During the upward movement of the secondary plunger 2, the secondary piston section 27 abuts against the lower side of the primary piston 1 and the primary check valve 14 (i.e., a two-stage structure), thereby driving the primary piston 1 to move upward. At this time, the force exerted on the primary check valve 14 from the primary oil chamber 230 side is less than the force exerted from the secondary oil chamber 240 side, and the primary check valve 14 opens to connect the primary oil chamber 230 and the secondary oil chamber 240. During the downward movement of the secondary plunger 2, the secondary piston section 27 separates from the primary piston 1 and the primary check valve 14. When the secondary piston section 27 separates from the primary piston 1, the force exerted on the primary check valve 14 from the primary oil chamber 230 side is not less than the force exerted from the secondary oil chamber 240 side, and the primary check valve 14 closes to isolate the primary oil chamber 230 from the secondary oil chamber 240.

[0065] A secondary piston section 27 is equipped with a secondary check valve 3. The secondary check valve 3 is used to open when the pressure in the secondary oil chamber 240 is greater than the pressure in the tertiary oil chamber 4, so as to connect the secondary oil chamber 240 and the tertiary oil chamber 4. When the secondary check valve 3 is open, the secondary oil chamber 240 and the tertiary oil chamber 4 are connected through the secondary check valve 3; when the secondary check valve 3 is closed, the secondary oil chamber 240 and the tertiary oil chamber 4 are disconnected.

[0066] Please see Figure 4 and Figure 6 When the secondary piston section 27 separates from the primary piston 1, the primary oil chamber 230 of the hydraulic dual-cylinder dual-stage piston pump 100 in the no-load state is larger than the primary oil chamber 230 of the hydraulic dual-cylinder dual-stage piston pump 100 in the loaded state. When the hydraulic dual-cylinder dual-stage piston pump 100 is in the no-load state, the working cylinder 400 has no external load, the secondary piston 2 is at its lowest point, and the primary piston 1 is in its initial position. At this time, the vertical distance between the secondary piston 2 and the primary piston 1 is L1. Please refer to... Figure 6When the hydraulic dual-cylinder dual-stage piston pump 100 is under load, the working cylinder 400 is externally loaded, the secondary piston 2 is at its lowest point, and the primary piston 1 is insufficient to return to its initial position. At this time, the vertical distance between the secondary piston 2 and the primary piston 1 is L2, and L2 > L1. This results in the cavity volume of the primary oil chamber 230 in the unloaded state being larger than that in the loaded state. The value of L1 can be zero or approximately zero. Because the hydraulic dual-cylinder dual-stage piston pump 100 has a dual-stage structure, the flow rate can be switched between unloaded and loaded states, thereby improving the working efficiency of the hydraulic dual-cylinder dual-stage piston pump 100 when unloaded.

[0067] The hydraulic dual-cylinder dual-stage piston pump 100 of the present invention forms a secondary oil chamber 240 and a tertiary oil chamber 4 between the secondary piston 2 and the cylinder body 200. A secondary check valve 3 is provided on the secondary piston 2, connecting the secondary oil chamber 240 and the tertiary oil chamber 4. The secondary check valve 3 opens when the pressure in the secondary oil chamber 240 is greater than the pressure in the tertiary oil chamber 4, thereby forming a dual-cylinder structure. This enables the hydraulic dual-cylinder dual-stage piston pump 100 to perform work throughout its entire stroke, achieving effects such as smoothing alternating loads, reducing vibration, and improving energy utilization efficiency. Furthermore, the hydraulic dual-cylinder dual-stage piston pump 100... The pump 100 is equipped with a first-stage piston 1 and a first-stage check valve 14, forming a two-stage structure. This two-stage structure enables the hydraulic dual-cylinder dual-stage piston pump 100 to switch between no-load and load conditions, thereby improving the no-load working efficiency of the hydraulic dual-cylinder dual-stage piston pump 100. Thus, the hydraulic dual-cylinder dual-stage piston pump 100 adopts a combination of dual-cylinder and dual-stage structures. The dual-cylinder and dual-stage structures are linked in structure and function, thereby achieving efficient and stable operation under load, while also improving the no-load working efficiency.

[0068] The specific configuration of the dual-stage structure can be set according to the actual situation. As long as the dual-stage structure can realize the switching of flow rate of the hydraulic dual-cylinder dual-stage piston pump 100 under no-load and load conditions, and realize the isolation and connection between the first-stage oil chamber 230 and the second-stage oil chamber 240, it is acceptable.

[0069] Optionally, please refer to Figure 1 , Figure 2 and Figure 4In this embodiment, the first-stage piston 1 includes a one-way valve sleeve 11, a one-way valve core 12, and an elastic reset member 13. The one-way valve sleeve 11 is slidably disposed within the piston chamber 210. The one-way valve core 12 is located above the one-way valve sleeve 11 and is movable relative to the one-way valve sleeve 11. The first-stage one-way valve 14 is disposed between the one-way valve core 12 and the one-way valve sleeve 11. The elastic reset member 13 abuts against the one-way valve core 12 and the inner wall of the piston chamber 210. When the one-way valve core 12 abuts against the one-way valve sleeve 11, the first-stage one-way valve 14 is closed. When the one-way valve core 12 separates from the one-way valve sleeve 11, the first-stage one-way valve 14 is open.

[0070] Specifically, the primary piston 1 consists of a one-way valve sleeve 11, a one-way valve core 12, and an elastic return member 13. The elastic return member 13 can be a spring, etc. The following description will use a spring as an example. The one-way valve sleeve 11 is slidably disposed within the piston chamber 210. During the upward movement of the secondary piston 2, the secondary piston portion 27 abuts against the lower side of the primary piston 1, thereby driving the primary piston 1 to move upward. Within the piston chamber 210, the primary piston 1 forms a primary oil chamber 230 located above the primary piston 1 and a secondary oil chamber 240 located below the primary piston 1. When the primary piston 1 moves upward, the cavity volume of the primary oil chamber 230 decreases; when the primary piston 1 moves downward, the cavity volume of the primary oil chamber 230 increases.

[0071] Furthermore, when the secondary piston section 27 separates from the primary piston 1, the check valve core 12 abuts against the check valve sleeve 11. At this time, the force exerted on the primary check valve 14 from the primary oil chamber 230 side is not less than the force exerted from the secondary oil chamber 240 side, and the primary check valve 14 closes. The check valve core 12 is provided with an abutment part. During the upward movement of the secondary plunger 2, the secondary piston section 27 will successively abut against the abutment part of the check valve core 12 and the check valve sleeve 11 from the lower side, so that after the check valve core 12 separates from the check valve sleeve 11, the secondary piston section 27 drives the check valve sleeve 11 and the check valve core 12 to move upward. At this time, the force exerted on the primary check valve 14 from the primary oil chamber 230 side is less than the force exerted from the secondary oil chamber 240 side, and the primary check valve 14 opens.

[0072] When the secondary piston section 27 is separated from the primary piston 1, the primary piston 1 (i.e., the one-way valve sleeve 11) of the hydraulic dual-cylinder dual-stage piston pump 100 in the no-load state is located below the primary piston 1 (i.e., the one-way valve sleeve 11) of the hydraulic dual-cylinder dual-stage piston pump 100 in the load state.

[0073] Further, please refer to Figure 1 , Figure 2 and Figure 4 In this embodiment, the primary check valve 14 includes a clearance hole 111 and an oil passage hole 112 disposed through the check valve sleeve 11, and an abutment protrusion 121 and a sealing portion 122 disposed on the check valve core 12. When the check valve core 12 abuts against the check valve sleeve 11, the abutment protrusion 121 passes downward through the check valve sleeve 11 from the clearance hole 111, and the sealing portion 122 seals the oil passage hole 112. When the check valve core 12 separates from the check valve sleeve 11, the secondary piston portion 27 abuts against the lower side of the abutment protrusion 121, and the sealing portion 122 separates from the oil passage hole 112.

[0074] Specifically, the one-way valve sleeve 11 has a clearance hole 111 and an oil passage hole 112. The one-way valve core 12 has an abutment protrusion 121 corresponding to the clearance hole 111 to form an abutment portion, and the one-way valve core 12 has a sealing portion 122 corresponding to the oil passage hole 112. Since the height of the abutment protrusion 121 is greater than the depth of the clearance hole 111, when the secondary piston portion 27 separates from the primary piston 1, the one-way valve core 12 can abut against the upper side of the one-way valve sleeve 11 under the action of the elastic reset member 13, so that the one-way valve core 12 can block the oil passage hole 112 from the upper side, thereby isolating the primary oil chamber 230 from the secondary oil chamber 240, and also allowing the abutment protrusion 121 to extend downward out of the clearance hole 111, so that the abutment protrusion 121 protrudes downward out of the lower surface of the one-way valve sleeve 11. As the secondary plunger 2 slides upward, the abutment protrusion 121 protrudes downward from the lower surface of the check valve sleeve 11. The secondary piston 27 first abuts against the abutment protrusion 121 of the check valve core 12, causing the check valve core 12 to move upward relative to the check valve sleeve 11 and compress the elastic reset member 13. This separates the check valve core 12 from the check valve sleeve 11. At this point, the force exerted on the primary check valve 14 from the primary oil chamber 230 side is less than the force from the secondary oil chamber 240 side. The blockage of the oil passage 112 by the check valve core 12 is released, and the primary check valve 14 opens, allowing the primary oil chamber 230 and the secondary oil chamber 240 to connect through the oil passage 112. As the secondary plunger 2 continues to slide upward, the secondary piston 27 abuts against the check valve sleeve 11 again, causing the check valve sleeve 11 and the check valve core 12 to move upward together and continue compressing the elastic reset member 13. When the secondary plunger 2 slides upward to the highest point and then slides downward, the secondary piston part 27 separates from the one-way valve sleeve 11. The one-way valve sleeve 11 and the one-way valve core 12 can automatically move downward to reset under the action of the elastic reset member 13, so that the one-way valve core 12 re-blocks the oil passage 112 from the upper side, so as to isolate the primary oil chamber 230 from the secondary oil chamber 240, and also so that the abutment protrusion 121 extends downward again to avoid the hole 111.

[0075] The check valve sleeve 11 is typically located below the oil inlet 220; that is, the check valve sleeve 11 at the highest point is located below the oil inlet 220. The specific shape and style of the check valve sleeve 11 can be set according to actual conditions. Optionally, please refer to [link / reference needed]. Figure 1 , Figure 2 and Figure 4 In this embodiment, the one-way valve sleeve 11 includes a cylindrical portion 113 and a plate-shaped portion 114. The cylindrical portion 113 is arranged in a cylindrical shape extending vertically, and the cylindrical portion 113 and the inner wall of the piston chamber 210 form a sliding fit vertically. The plate-shaped portion 114 is disposed at the lower end of the cylindrical portion 113, and a clearance hole 111 and an oil passage hole 112 are provided through the plate-shaped portion 114. The lower end of the one-way valve core 12 extends into the cylindrical portion 113, and an abutment protrusion 121 is provided on the lower end surface of the one-way valve core 12. When the one-way valve core 12 abuts against the one-way valve sleeve 11, the lower end surface of the one-way valve core 12 abuts against the upper side of the plate-shaped portion 114. When the one-way valve core 12 is separated from the one-way valve sleeve 11, the lower end surface of the one-way valve core 12 and the plate-shaped portion 114 are arranged vertically at intervals.

[0076] Specifically, the check valve sleeve 11 is composed of a cylindrical portion 113 and a plate-shaped portion 114, making the check valve sleeve 11 an upward-opening cylindrical shape. Through the sliding fit between the cylindrical portion 113 and the inner wall of the piston chamber 210, the vertical movement of the check valve sleeve 11 within the piston chamber 210 can be guided. Furthermore, the lower end of the check valve core 12 extends into the check valve sleeve 11 from the upper opening of the cylindrical portion 113, thus achieving the installation and positioning of the check valve sleeve 11 and the check valve core 12.

[0077] The plate-shaped portion 114 may be provided with one, two, three or more oil passage holes 112. Optionally, please refer to [reference needed]. Figure 1 and Figure 2 In this embodiment, multiple oil passage holes 112 are provided at intervals along the circumference of the cylindrical portion 113, and the multiple oil passage holes 112 are arranged around the avoidance hole 111.

[0078] Specifically, a clearance hole 111 is provided in the middle of the plate-shaped portion 114, and a plurality of oil passage holes 112 are provided on the plate-shaped portion 114. The plurality of oil passage holes 112 are arranged around the clearance hole 111. In this way, the provision of a plurality of oil passage holes 112 on the plate-shaped portion 114 facilitates the hydraulic oil in the primary oil chamber 230 to enter the secondary oil chamber 240 evenly through the plurality of oil passage holes 112.

[0079] A sealing portion 122 is provided on the check valve core 12. The sealing portion 122 can be disposed on the lower end face of the check valve core 12; the sealing portion 122 can also be disposed on the peripheral side face of the check valve core 12. Optionally, please refer to... Figure 1 , Figure 2 and Figure 4 In this embodiment, the sealing part 122 is an annular protrusion 122a provided on the peripheral side of the one-way valve core 12, and the lower surface of the annular protrusion 122a is flush with the lower end surface of the one-way valve core 12.

[0080] Specifically, when the one-way valve core 12 abuts against the one-way valve sleeve 11, the lower surface of the annular protrusion 122a abuts against the upper edge of the oil passage 112, so that the annular protrusion 122a can block the oil passage 112. This way of setting the blocking part 122 is beneficial to increase the blocking area of ​​the blocking part 122 on the oil passage 112 and ensure the blocking effect of the blocking part 122 on the oil passage 112.

[0081] The elastic reset member 13 is disposed between the one-way valve core 12 and the inner wall of the piston chamber 210. The specific arrangement of the elastic reset member 13 can be set according to the actual situation. For example, the elastic reset member 13 can be disposed between the upper end face of the one-way valve core 12 and the upper inner wall of the piston chamber 210.

[0082] Optionally, please refer to Figure 1 , Figure 2 and Figure 4 In this embodiment, the lower end of the elastic reset member 13 is sleeved on the upper end of the one-way valve core 12, the lower end of the elastic reset member 13 abuts against the upper side of the annular protrusion 122a, and the upper end of the elastic reset member 13 abuts against the lower side of the inner wall of the piston chamber 210.

[0083] Specifically, the lower end of the elastic reset member 13 is sleeved on the upper end of the one-way valve core 12, thus achieving the installation and positioning between the elastic reset member 13 and the one-way valve core 12 and preventing the elastic reset member 13 from disengaging from the one-way valve core 12. The one-way valve core 12 is arranged in a shape that is smaller at the top and larger at the bottom, so that an annular protrusion 122a is formed on the peripheral side of the one-way valve core 12. In this way, through the abutting cooperation between the upper surface of the annular protrusion 122a and the elastic reset member 13, the elastic reset member 13 can be limited in both vertical and upward directions.

[0084] When the check valve core 12 abuts against the upper side of the check valve sleeve 11, the clearance hole 111 on the check valve sleeve 11 is also blocked by the check valve core 12 to prevent hydraulic oil in the primary oil chamber 230 from entering the secondary oil chamber 240 through the clearance hole 111. The check valve core 12 can block the clearance hole 111 by only blocking the clearance hole 111 with the abutment protrusion 121; or it can block the clearance hole 111 by simultaneously blocking the clearance hole 111 with the abutment protrusion 121 and the lower end face of the check valve core 12.

[0085] Optionally, please refer to Figure 1 , Figure 2 and Figure 4In this embodiment, the clearance hole 111 and the abutment protrusion 121 are in clearance fit; when the secondary piston part 27 separates from the primary piston 1 (that is, when the one-way valve core 12 abuts against the one-way valve sleeve 11), the one-way valve core 12 blocks the clearance between the clearance hole 111 and the abutment protrusion 121.

[0086] Specifically, the fit between the clearance hole 111 and the abutment protrusion 121 is a clearance fit, with a gap between them. This prevents interference between the abutment protrusion 121 and the inner wall of the clearance hole 111 when the secondary piston 27 abuts against the abutment protrusion 121. This facilitates the upward movement of the one-way valve core 12 relative to the one-way valve sleeve 11 via the secondary piston 27. At this time, the clearance hole 111 also functions as an oil passage hole 112, allowing hydraulic oil in the primary oil chamber 230 to enter the secondary oil chamber 240 through the gap between the clearance hole 111 and the abutment protrusion 121. When the secondary piston 27 separates from the primary piston 1, the lower end face of the one-way valve core 12 blocks the gap between the clearance hole 111 and the abutment protrusion 121, thus effectively blocking the clearance hole 111 through the abutment protrusion 121 and the lower end face of the one-way valve core 12.

[0087] As described above, the hydraulic dual-cylinder, two-stage piston pump 100 may include a portion of the cylinder body 200. Optionally, please refer to [link to relevant documentation]. Figures 4 to 7 A bushing 5 is provided inside the cylinder body 200. The bushing 5 is fitted outside the secondary piston part 27. The upper side of the bushing 5, the upper end face of the secondary piston part 27 and the lower end face of the primary piston 1 cooperate with the piston chamber 210 to form a secondary oil chamber 240. The bushing 5 is fitted outside the secondary piston part 27, and a tertiary oil chamber 4 is formed between the secondary piston part 27 and the bushing 5.

[0088] Specifically, the bushing 5 is fixedly fitted inside the lower end of the piston chamber 210. The upper side of the bushing 5, the upper end face of the secondary piston portion 27, the lower end face of the primary piston 1, and the inner wall of the piston chamber 210 enclose a secondary oil chamber 240. A tertiary oil chamber 4 is formed between the inner circumferential side of the bushing 5 and the secondary piston portion 27. The bushing 5 is fitted outside the secondary piston portion 27 (i.e., the upper end of the secondary plunger 2). Please refer to [link to relevant documentation]. Figure 4 and Figure 6 When the secondary plunger 2 is at its lowest point, the upper end face of the secondary piston 27 is flush with or nearly flush with the upper end face of the bushing 5.

[0089] A third-stage oil cavity 4 is formed between the secondary plunger 2 and the bushing 5. Optionally, please refer to [link / reference]. Figure 1 and Figure 2In this embodiment, the lower end face of the secondary piston 27 is a downward-facing first annular surface 22, and the inner peripheral side of the bushing 5 is provided with an upward-facing second annular surface 52. The second annular surface 52 is located below the first annular surface 22, and a third-stage oil cavity 4 is formed between the second annular surface 52 and the first annular surface 22.

[0090] Specifically, as described above, the diameter of the secondary piston portion 27 of the secondary plunger 2 is larger than the diameter of the rod portion 28, causing the lower end face of the secondary piston portion 27 to form a downward-facing first annular surface 22, thus forming the first annular surface 22 on the circumferential side of the secondary plunger 2. The shape of the inner circumferential side of the bushing 5 is usually adapted to the shape of the circumferential side of the secondary plunger 2, thus forming an upward-facing second annular surface 52 on the inner circumferential side of the bushing 5. The first annular surface 22 and the second annular surface 52 are vertically opposite each other, so that the first annular surface 22, the second annular surface 52, and the inner circumferential side of the bushing 5 located between the first annular surface 22 and the second annular surface 52 enclose and form a three-stage oil cavity 4.

[0091] When the secondary plunger 2 is at its lowest point, the first annular surface 22 can abut against the second annular surface 52; alternatively, the first annular surface 22 can have a pre-existing gap with the second annular surface 52 in the vertical and upward directions. Alternatively, please refer to... Figure 1 , Figure 2 , Figure 4 and Figure 6 In this embodiment, when the secondary plunger 2 is at its lowest point, a gap is reserved between the first annular surface 22 and the second annular surface 52 in the vertical direction. As the secondary plunger 2 slides upward, the gap between the first annular surface 22 and the second annular surface 52 gradually increases, thereby gradually increasing the cavity volume of the tertiary oil cavity 4. Conversely, as the secondary plunger 2 slides downward, the gap between the first annular surface 22 and the second annular surface 52 gradually decreases, thereby gradually decreasing the cavity volume of the tertiary oil cavity 4.

[0092] The three-stage oil chamber 4 connects to the oil outlet 250 of the cylinder block 200. Optionally, please refer to [link / reference]. Figure 2 , Figures 4 to 7 In this embodiment, a bushing oil passage 51 is provided through the bushing 5, connecting the oil outlet 250 and the third-stage oil chamber 4. The bushing oil passage 51 on the bushing 5 facilitates the connection between the third-stage oil chamber 4 and the oil outlet 250 of the cylinder block 200.

[0093] The specific configuration of the bushing oil passage 51 can be set according to the actual situation. Optionally, please refer to [link / reference needed]. Figure 2 , Figures 4 to 7In this embodiment, the bushing oil passage 51 extends radially along the bushing 5 and is located above the second annular surface 52. This arrangement of the bushing oil passage 51 results in a relatively short oil path and relatively low fluid resistance.

[0094] The secondary piston section 27 is typically provided with a plunger oil passage 21 connecting the secondary oil chamber 240 and the tertiary oil chamber 4, so that the secondary one-way valve 3 is disposed within the plunger oil passage 21. The specific arrangement of the plunger oil passage 21 on the secondary piston section 27 can be set according to the actual situation. Optionally, please refer to [reference needed]. Figure 1 and Figure 2 In this embodiment, the plunger oil passage 21 penetrates the upper end face of the secondary plunger 2 and the first annular surface 22.

[0095] Specifically, the upper end of the plunger oil passage 21 penetrates the upper end face of the secondary plunger 2, and the lower end of the plunger oil passage 21 penetrates the lower end face of the secondary plunger 2 (i.e., the first annular surface 22). This is beneficial to make the oil passage of the plunger oil passage 21 shorter, so that the liquid resistance of the plunger oil passage 21 can be relatively small.

[0096] Further, please refer to Figure 1 and Figure 2 In this embodiment, the plunger oil passage 21 includes an installation channel 23 and a connecting channel 24. The installation channel 23 is disposed on the upper end face of the secondary plunger 2, and one end of the installation channel 23 is opened on the upper side of the first annular surface 22. The secondary one-way valve 3 is disposed in the installation channel 23. One end of the connecting channel 24 penetrates the inner channel wall of the installation channel 23, and the other end of the connecting channel 24 penetrates the first annular surface 22. Multiple connecting channels 24 are provided at intervals along the circumference of the installation channel 23.

[0097] Specifically, the plunger oil passage 21 consists of an installation channel 23 and multiple connecting channels 24. The installation channel 23 is provided on the upper end face of the secondary plunger 2 to facilitate the installation of the secondary check valve 3 in the plunger oil passage 21. The multiple connecting channels 24 facilitate the uniform flow of hydraulic oil in the secondary oil chamber 240 into the tertiary oil chamber 4 through the multiple connecting channels 24.

[0098] The upper end of the connecting channel 24 penetrates the inner wall of the mounting channel 23, and the lower end of the connecting channel 24 penetrates the lower end face (i.e., the first annular surface 22) of the secondary piston section 27. The specific configuration of the connecting channel 24 can be set according to actual conditions; optionally, please refer to [reference needed]. Figure 1 and Figure 2In this embodiment, the connecting channel 24 is a straight hole extending along a straight line. The extending direction of the connecting channel 24 is gradually inclined from top to bottom away from the central axis of the secondary plunger 2. For example, the upper end of the connecting channel 24 passes through the connection between the side wall and the bottom wall of the mounting channel 23, and the lower end of the connecting channel 24 passes through the connection between the first annular surface 22 and the peripheral side of the rod 28. By setting the connecting channel 24 in this way, the oil passage of the connecting channel 24 is relatively short and the liquid resistance of the connecting channel 24 is relatively small.

[0099] During the upward movement of the secondary plunger 2, the secondary piston section 27 abuts against the primary piston 1. The secondary piston section 27 can abut against the primary piston 1 through the secondary check valve 3 and / or other parts provided on the secondary piston section 27. Optionally, please refer to Figure 1 and Figure 2 In this embodiment, the secondary check valve 3 is disposed on the upper end face of the secondary piston portion 27; when the secondary piston portion 27 abuts against the primary piston 1, the secondary check valve 3 abuts against the lower side of the abutment protrusion 121. The abutment protrusion 121 is normally disposed downward in the middle of the primary piston 1, and the secondary check valve 3 is also disposed in the middle of the upper end face of the secondary piston portion 27. Therefore, during the upward movement of the secondary plunger 2, the secondary piston portion 27 abuts against the abutment protrusion 121 through the secondary check valve 3.

[0100] The secondary check valve 3 opens when the pressure in the secondary oil chamber 240 is greater than the pressure in the tertiary oil chamber 4. The specific design of the secondary check valve 3 can be set according to actual conditions. Optionally, please refer to... Figure 1 and Figure 2 In this embodiment, the secondary check valve 3 includes a valve seat 31 and a valve ball 33. The valve seat 31 is disposed in the plunger oil passage 21, and the valve seat 31 is provided with an oil inlet channel 32 that connects the secondary oil chamber 240 and the plunger oil passage 21. The valve ball 33 is located on the side of the oil inlet channel 32 away from the port of the secondary oil chamber 240. When the plunger 2 slides downward, the valve ball 33 blocks the port of the oil inlet channel 32 away from the secondary oil chamber 240, so that the secondary check valve 3 is closed. When the plunger 2 slides upward, the valve ball 33 separates from the valve seat 31 and opens the port of the oil inlet channel 32, so that the secondary check valve 3 is opened.

[0101] Specifically, the valve seat 31 is arranged in a cylindrical shape extending vertically to form an oil inlet channel 32 on its inner side. The valve seat 31 is positioned at the groove of the mounting channel 23. The valve ball 33 is located below the valve seat 31 and within the mounting channel 23, and the diameter of the valve ball 33 is larger than the inner diameter of the valve seat 31. When the pressure in the secondary oil chamber 240 is greater than the pressure in the tertiary oil chamber 4, the valve ball 33 moves downward under the pressure difference, separating from the valve seat 31. The valve ball 33 moves to its lowest point, causing the secondary check valve 3 to open. When the secondary plunger 2 moves downward, the valve ball 33 moves upward, reaching its highest point and blocking the lower end of the oil inlet channel 32, causing the secondary check valve 3 to close.

[0102] Valve seat 31 can be fixed in the mounting channel 23 by means of thread fixing or interference fit, etc. Optionally, please refer to Figure 1 and Figure 2 In this embodiment, an annular limiting surface 25 is provided on the inner wall of the plunger oil passage 21, and the annular limiting surface 25 abuts against the side of the valve seat 31 away from the secondary oil chamber 240.

[0103] Specifically, an upward-facing annular limiting surface 25 is provided on the inner groove side wall of the installation channel 23. The annular limiting surface 25 abuts against the upper side of the valve seat 31. In this way, the valve seat 31 can be installed and positioned in the installation channel 23 through the abutting cooperation between the valve seat 31 and the annular limiting surface 25.

[0104] Optionally, please refer to Figure 1 and Figure 2 In this embodiment, a first annular seal 26 is sleeved between the secondary plunger 2 and the bushing 5, and the first annular seal 26 is located on the lower side of the tertiary oil chamber 4.

[0105] Specifically, a first annular mounting groove is provided on the peripheral side of the rod portion 28 of the secondary plunger 2. The first annular mounting groove is located below the first annular surface 22 and the second annular surface 52. A first annular seal 26 is provided at the first annular mounting groove. Thus, by providing the first annular seal 26 between the secondary plunger 2 and the bushing 5, the sealing between the secondary plunger 2 and the bushing 5 can be guaranteed.

[0106] Optionally, please refer to Figure 2 and Figure 4 In this embodiment, a second annular seal 53 is fitted between the bushing 5 and the inner wall of the piston chamber 210, and the second annular seal 53 is located on the lower side of the bushing oil passage 51.

[0107] Specifically, a second annular mounting groove is provided on the outer peripheral side of the bushing 5. The second annular mounting groove is located below the second annular surface 52 and the oil outlet 250. A second annular seal 53 is provided at the second annular mounting groove. Thus, by providing the second annular seal 53 between the bushing 5 and the inner wall of the piston chamber 210, the sealing between the bushing 5 and the inner wall of the piston chamber 210 can be guaranteed.

[0108] Optionally, please refer to Figures 4 to 7 In this embodiment, both the oil inlet 220 and the oil outlet 250 extend radially along the bushing 5, and the bushing oil passage 51, the oil inlet 220, and the oil outlet 250 extend in the same direction. This arrangement of the oil inlet 220 and the oil outlet 250 results in relatively short oil passages for the oil inlet 220 and the oil outlet 250, thus reducing the fluid resistance of the oil inlet 220 and the oil outlet 250.

[0109] Optionally, please refer to Figures 4 to 7 In this embodiment, the oil inlet 220 is located above the oil outlet 250, and the oil inlet 220 and the oil outlet 250 are located on both sides of the piston chamber 210 in the extending direction of the oil inlet 220.

[0110] Please see Figures 4 to 7 An oil suction check valve 260 is installed at the oil inlet 220. The oil suction check valve 260 is used to open when the pressure in the first-stage oil chamber 230 is less than the pressure in the oil tank 500 at the other end of the oil inlet 220. An oil outlet check valve 270 is installed at the oil outlet 250. The oil outlet check valve 270 is used to open when the pressure in the third-stage oil chamber 4 is greater than the pressure in the working cylinder 400 at the other end of the oil outlet 250. Only two check valves are installed on the piston chamber 210, namely the oil suction check valve 260 and the oil outlet check valve 270. The oil suction check valve 260 and the oil outlet check valve 270 are connected to the first-stage oil chamber 230 and the third-stage oil chamber 4, respectively. The oil suction check valve 260 and the oil outlet check valve 270 are installed in opposite directions, forming the oil inlet and oil outlet of the cylinder body 200, respectively. Furthermore, a secondary check valve 3 is added to the secondary plunger 2, which can switch to dual cylinder mode, allowing the secondary oil chamber 240 and the tertiary oil chamber 4 to share a pair of inlet and outlet nozzles. This simplifies the structure of the hydraulic dual-cylinder dual-stage plunger pump 100, making the hydraulic dual-cylinder dual-stage plunger pump 100 occupy a smaller space volume, which can meet the requirements of light weight and small size of handheld hydraulic tools, thus making the hydraulic dual-cylinder dual-stage plunger pump 100 suitable for handheld hydraulic tools.

[0111] Please see Figures 4 to 7When the secondary plunger 2 slides upward and the secondary piston part 27 separates from the primary piston 1, the primary oil chamber 230 and the secondary oil chamber 240 are separated, the secondary oil chamber 240 becomes smaller, the tertiary oil chamber 4 becomes larger, and the secondary check valve 3 and the oil outlet 250 open; when the secondary plunger 2 slides upward and the secondary piston part 27 abuts against the primary piston 1, the primary oil chamber 230 and the secondary oil chamber 240 are connected, the primary oil chamber 230 becomes smaller, the secondary oil chamber 240 and the tertiary oil chamber 4 become larger, the secondary check valve 3 opens, and the oil outlet 250 closes; when the secondary plunger 2 slides downward, the primary oil chamber 230 and the secondary oil chamber 240 are separated, the primary oil chamber 230 becomes larger, the oil inlet 220 opens, the secondary oil chamber 240 and the tertiary oil chamber 4 become smaller, the secondary check valve 3 closes, and the oil outlet 250 opens.

[0112] Specifically, please refer to Figure 4 , Figure 5 , Figure 8 and Figure 9 When there is no external load on the working cylinder 400, the secondary plunger 2 is at its lowest point. The motor 300a is energized and rotates, driving the eccentric wheel 312 to rotate via the reduction gearbox 320. The eccentric wheel 312 pushes the push-pull rod 311 upwards, and the primary piston 1 moves upwards synchronously. The cavity volumes of the secondary oil chamber 240 and the tertiary oil chamber 4 increase, and they simultaneously connect with the primary oil chamber 230. The hydraulic oil in the primary oil chamber 230 fills the secondary oil chamber 240 through the oil passage 112. At the same time, the secondary one-way valve 3 opens, and the hydraulic oil in the secondary oil chamber 240 fills the tertiary oil chamber 4 through the plunger oil passage 21. When the eccentric wheel 312 rotates to its highest point, the secondary plunger 2 is at its highest point, and the secondary oil chamber 240 and the tertiary oil chamber 4 stop drawing oil. At this time, the secondary oil chamber 240 and the tertiary oil chamber 4 are completely filled. Figure 8 As indicated by the thick solid arrow, during this process, the oil outlet check valve 270 is closed, and the flow path of the hydraulic oil is: primary oil chamber 230 → oil passage 112 → secondary oil chamber 240 → plunger oil passage 21 → tertiary oil chamber 4.

[0113] As the eccentric wheel 312 continues to rotate from its highest point, the secondary plunger 2 moves downward from its highest point. Under the action of the elastic reset member 13, the one-way valve core 12 and the one-way valve sleeve 11 come into contact (at this time, the secondary plunger 2 separates from the primary piston 1), isolating the primary oil chamber 230 from the secondary oil chamber 240 and the tertiary oil chamber 4. Under the action of the elastic reset member 13, the one-way valve core 12 and the one-way valve sleeve 11 move downward with the secondary plunger 2, simultaneously compressing the secondary oil chamber 240 and the tertiary oil chamber 4. This forces the hydraulic oil in the secondary oil chamber 240 and the tertiary oil chamber 4 into the working cylinder 400 through the outlet one-way valve 270, pushing the piston in the working cylinder 400 to move. For example... Figure 9The thick solid arrow indicates that the hydraulic oil flow path is: secondary oil chamber 240 → plunger oil passage 21 → tertiary oil chamber 4 → oil inlet 220 → working cylinder 400. During this process, the cavity volume of the primary oil chamber 230 increases, drawing in oil again. For example... Figure 9 As indicated by the dotted arrow, the hydraulic oil flow path is: oil tank 500 → oil inlet 220 → primary oil chamber 230. One rotation of motor 300a pushes nearly the maximum oil volume in the secondary oil chamber 240 (when the secondary plunger 2 reaches its lowest point, the gap between the secondary plunger 2 and the primary piston 1 is small). A large oil volume accelerates the piston rod movement speed in the working cylinder 400 under no-load conditions, thus improving efficiency.

[0114] Please see Figure 6 and Figure 7 When there is an external load on the working cylinder 400, the one-way valve sleeve 11 and the one-way valve core 12 are insufficient to return to the lowest point under the action of the elastic reset member 13, but the one-way valve core 12 and the one-way valve sleeve 11 are still in contact. The secondary plunger 2 is at the lowest point, the motor 300a is energized and rotates, and drives the eccentric wheel 312 to rotate through the reduction gearbox 320. The eccentric wheel 312 pushes the push-pull rod 311 to move upward. At this time, the secondary one-way valve 3 opens, and the secondary oil chamber 240 and the tertiary oil chamber 4 are connected. When the secondary plunger 2 does not contact the primary piston 1, the total cavity volume of the secondary oil chamber 240 and the tertiary oil chamber 4 becomes smaller, and the hydraulic oil in the secondary oil chamber 240 and the tertiary oil chamber 4 is forced into the working cylinder 400 through the oil outlet one-way valve 270, pushing the piston rod in the working cylinder 400 to move. Figure 10 As indicated by the thick solid arrow, the flow path of the high-pressure hydraulic oil is: secondary oil chamber 240 → plunger oil passage 21 → tertiary oil chamber 4 → oil inlet 220 → working cylinder 400. The oil intake during this upward stroke is the volume of the secondary oil chamber 240 and the tertiary oil chamber 4 compressed by the secondary plunger 2, resulting in high pressure, small volume, and smooth operation.

[0115] Please see Figure 5 As motor 300a continues to rotate, when the secondary piston 27 of the secondary plunger 2 contacts the primary piston 1, it pushes open the elastic reset member 13, connecting the secondary oil chamber 240, the tertiary oil chamber 4, and the primary oil chamber 230. At this time, the oil outlet check valve 270 closes, increasing the cavity volume of the secondary oil chamber 240 and the tertiary oil chamber 4, while decreasing the cavity volume of the primary oil chamber 230. The hydraulic oil in the primary oil chamber 230 enters the secondary oil chamber 240 and the tertiary oil chamber 4. Meanwhile, the primary piston 1 continues to move upward with the secondary plunger 2. Figure 8 As indicated by the thick solid arrow, during this process, the oil outlet check valve 270 is closed, and the flow path of the hydraulic oil is: primary oil chamber 230 → oil passage 112 → secondary oil chamber 240 → plunger oil passage 21 → tertiary oil chamber 4.

[0116] As the eccentric wheel 312 continues to rotate from its highest point, the secondary plunger 2 moves downward from its highest point, and the secondary check valve 3 closes, isolating the secondary oil chamber 240 from the tertiary oil chamber 4. Under the action of the elastic reset member 13, the check valve core 12 abuts against the check valve sleeve 11, isolating the primary oil chamber 230 from the secondary oil chamber 240. As the secondary plunger 2 moves downward, the cavity volume of the secondary oil chamber 240 decreases, and the primary piston 1 moves downward to fill the reduced volume of the secondary oil chamber 240. The cavity volume of the primary oil chamber 230 increases, and the suction check valve 260 opens. The hydraulic oil in the oil tank 500 is sequentially drawn into the primary oil chamber 230 through the filter 280, the suction check valve 260, and the inlet 220. Figure 11 The dashed arrow indicates that the hydraulic oil flow path is: oil tank 500 → oil inlet 220 → primary oil chamber 230. The secondary plunger 2 moves downwards, compressing the cavity volume of the tertiary oil chamber 4, forcing high-pressure hydraulic oil through the outlet check valve 270 into the working cylinder 400, continuing to push the piston rod within the working cylinder 400. Wherein, as... Figure 11 As indicated by the thick solid arrow, the flow path of the high-pressure hydraulic oil is: third-stage oil chamber 4 → oil inlet 220 → working cylinder 400. The oil intake during this pull-down stroke is the volume of the cavity of the third-stage oil chamber 4 compressed by the second-stage plunger 2, which is close to the oil intake during the push-up stroke, thus achieving a smooth switching between the push and pull strokes.

[0117] Thus, the secondary oil chamber 240 and the tertiary oil chamber 4 serve as the oil inlet chambers when the secondary plunger 2 pushes upward, and the tertiary oil chamber 4 serves as the oil inlet chamber when the secondary plunger 2 pulls downward, thereby enabling the hydraulic dual-cylinder dual-stage plunger pump 100 to perform work throughout its entire stroke. The hydraulic dual-cylinder dual-stage plunger pump 100 can achieve stable operation under load, reduce vibration, improve the output energy utilization efficiency of the drive device 300, and enhance the endurance of the hydraulic tool 1000.

[0118] Because the hydraulic dual-cylinder two-stage piston pump 100 combines a dual-cylinder structure and a two-stage structure, and the dual-cylinder structure and the two-stage structure are linked in structure and function, the hydraulic dual-cylinder two-stage piston pump 100 not only possesses all the advantages of a dual-cylinder piston pump, but also has the following advantages:

[0119] 1. Existing axial piston hydraulic pumps are variable pumps, which adjust the flow rate by changing the tilt angle of the swashplate through a servo valve. They have a complex structure. In contrast, the hydraulic double-cylinder double-stage piston pump 100 has a simple structure.

[0120] 2. Compared with existing two-stage pumps and pressure regulating valves, the hydraulic double-cylinder double-stage piston pump 100 has fewer parts and a simpler structure, and can achieve rapid operation under no-load conditions.

[0121] 3. Under the same structural volume, the hydraulic double-cylinder double-stage piston pump 100 can be better expanded into two or even more pump combinations to improve efficiency.

[0122] The present invention also provides a hydraulic tool, which can be a hydraulic pliers, etc. Figures 3 to 7 A preferred embodiment of the hydraulic tool provided by the present invention is shown.

[0123] Please see Figures 3 to 7 In this embodiment, the hydraulic tool 1000 includes a hydraulic dual-cylinder dual-stage piston pump 100, a drive device 300, a working cylinder 400, and an oil tank 500. The oil tank 500 is connected to the oil inlet 220 of the hydraulic dual-cylinder dual-stage piston pump 100; the working cylinder 400 is connected to the oil outlet 250 of the hydraulic dual-cylinder dual-stage piston pump 100; the drive device 300 is connected to the end of the secondary piston 2 of the hydraulic dual-cylinder dual-stage piston pump 100 away from the secondary piston section 27, and is used to drive the secondary piston section 27 to slide within the piston chamber 210. Since the hydraulic dual-cylinder dual-stage piston pump 100 adopts the technical solution of the above embodiment, it has the beneficial effects brought about by the technical solution of the above embodiment.

[0124] Optionally, please refer to Figure 3 In this embodiment, the drive device 300 is connected to the lower end of the secondary plunger 2 of the hydraulic double-cylinder double-stage plunger pump 100 through the eccentric wheel mechanism 310. The drive device 300 is used to drive the eccentric wheel mechanism 310 so as to drive the secondary plunger 2 to move up and down through the eccentric wheel mechanism 310.

[0125] Specifically, the eccentric wheel mechanism 310 includes a push-pull rod 311 and an eccentric wheel 312. The push-pull rod 311 is located at the lower end of the secondary plunger 2. The drive unit 300 is connected to the eccentric wheel 312 via a reduction gearbox 320. When the drive unit 300 is energized and rotates, it drives the eccentric wheel 312 to rotate via the reduction gearbox 320. The eccentric wheel 312 drives the push-pull rod 311, which in turn pushes the secondary plunger 2 upward. When the drive unit 300 rotates to 180°, the secondary plunger 2 reaches its highest point, the upward stroke of the secondary plunger 2 ends, and the eccentric wheel 312 begins to pull the secondary plunger 2 downward via the push-pull rod 311.

[0126] Optionally, please refer to Figure 3 In this embodiment, the hydraulic tool 1000 is a handheld hydraulic tool. Since the hydraulic dual-cylinder plunger pump 100 occupies a small space, it can meet the requirements of light weight and small size for handheld hydraulic tools, thus making the hydraulic dual-cylinder plunger pump 100 suitable for handheld hydraulic tools.

[0127] The above are merely preferred embodiments of the present invention and do not limit the scope of the patent. Any equivalent structural transformations made using the contents of the specification and drawings of the present invention under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the scope of patent protection of the present invention.

Claims

1. A hydraulic dual-cylinder, two-stage plunger pump, characterized in that, include: A cylinder body, wherein a piston chamber is formed within the cylinder body, and an oil inlet and an oil outlet communicating with the piston chamber are provided on the cylinder wall of the cylinder body; A primary piston is slidably mounted in the piston chamber, and the upper end face of the primary piston cooperates with the piston chamber to form a primary oil chamber, which is connected to the oil inlet. A secondary plunger has a secondary piston section at one end, which is slidably installed in the piston chamber and located on the side of the primary piston away from the primary oil chamber. The piston chamber forms a secondary oil chamber between the secondary piston section and the primary piston. The lower end face of the secondary piston section away from the secondary oil chamber cooperates with the piston chamber to form a tertiary oil chamber. The tertiary oil chamber is connected to the oil outlet. A first-stage check valve is provided on the first-stage piston and is used to open when the force exerted on the first-stage oil chamber is less than the force exerted on the second-stage oil chamber, so as to connect the first-stage oil chamber and the second-stage oil chamber. A secondary check valve is provided on the secondary piston section and is used to open when the pressure in the secondary oil chamber is greater than the pressure in the tertiary oil chamber, so as to connect the secondary oil chamber and the tertiary oil chamber.

2. The hydraulic dual-cylinder, two-stage piston pump according to claim 1, characterized in that, The primary piston includes: A one-way valve sleeve, wherein the one-way valve sleeve is slidably disposed within the piston chamber; A one-way valve core is located on the upper side of the one-way valve sleeve. The one-way valve core is movable up and down relative to the one-way valve sleeve. The first-stage one-way valve is disposed between the one-way valve core and the one-way valve sleeve. An elastic reset element abuts against the one-way valve core and the inner wall of the piston chamber; Specifically, when the one-way valve core abuts against the one-way valve sleeve, the first-stage one-way valve is closed; when the one-way valve core separates from the one-way valve sleeve, the first-stage one-way valve is open.

3. The hydraulic dual-cylinder, two-stage piston pump according to claim 2, characterized in that, The first-stage check valve includes a clearance hole and an oil passage hole that are disposed through the valve sleeve of the check valve, as well as an abutment protrusion and a sealing part disposed on the valve core of the check valve; Specifically, when the one-way valve core abuts against the one-way valve sleeve, the abutting protrusion passes downward through the one-way valve sleeve from the clearance hole, and the sealing part blocks the oil passage hole; when the one-way valve core separates from the one-way valve sleeve, the secondary piston part abuts against the lower side of the abutting protrusion, and the sealing part separates from the oil passage hole.

4. The hydraulic dual-cylinder, two-stage piston pump according to claim 3, characterized in that, The one-way valve sleeve includes: The cylindrical portion is arranged in a cylindrical shape extending vertically, and the cylindrical portion and the inner wall of the piston cavity form a sliding fit in vertically upward. A plate-shaped portion is provided at the lower end of the cylindrical portion in a sealing manner, and the plate-shaped portion is provided with the clearance hole and the oil passage hole through it; The lower end of the one-way valve core extends into the cylindrical portion, and the abutting protrusion is provided on the lower end surface of the one-way valve core; when the one-way valve core abuts against the one-way valve sleeve, the lower end surface of the one-way valve core abuts against the upper side of the plate-shaped portion; when the one-way valve core separates from the one-way valve sleeve, the lower end surface of the one-way valve core and the plate-shaped portion are arranged vertically at intervals.

5. The hydraulic dual-cylinder, two-stage piston pump according to claim 4, characterized in that, Multiple oil passage holes are provided at intervals along the circumference of the cylindrical portion, and the multiple oil passage holes are arranged around the clearance hole.

6. The hydraulic dual-cylinder, two-stage piston pump according to claim 4, characterized in that, The sealing part is an annular protrusion provided on the peripheral side of the one-way valve core, and the lower surface of the annular protrusion is flush with the lower end face of the one-way valve core.

7. The hydraulic dual-cylinder, two-stage piston pump according to claim 6, characterized in that, The lower end of the elastic reset member is sleeved on the upper end of the one-way valve core, the lower end of the elastic reset member abuts against the upper side of the annular protrusion, and the upper end of the elastic reset member abuts against the lower side of the inner wall of the piston chamber.

8. The hydraulic dual-cylinder, two-stage piston pump according to claim 3, characterized in that, The clearance hole and the abutment protrusion are in clearance fit; when the one-way valve core abuts against the one-way valve sleeve, the one-way valve core blocks the clearance between the clearance hole and the abutment protrusion.

9. The hydraulic dual-cylinder, two-stage piston pump according to claim 1, characterized in that, A bushing is provided inside the cylinder body. The bushing is fitted outside the secondary piston section. The upper side of the bushing, the upper end face of the secondary piston section and the lower end face of the primary piston section cooperate with the piston cavity to form the secondary oil chamber. The bushing is fitted outside the secondary piston section, and the secondary piston section and the bushing form the tertiary oil chamber.

10. A hydraulic tool, characterized in that, include: The hydraulic dual-cylinder two-stage piston pump as described in any one of claims 1-9; The oil tank is connected to the oil inlet of the hydraulic dual-cylinder dual-stage plunger pump; The working cylinder is connected to the oil outlet of the hydraulic dual-cylinder two-stage plunger pump; The drive unit is connected to the end of the secondary piston of the hydraulic dual-cylinder dual-stage piston pump away from the secondary piston section, and is used to drive the secondary piston section to slide within the piston chamber.

Images