Servo motor pump with three-port flow distribution structure

Abstract

A servo motor pump with a three-port flow distribution structure comprises a servo motor assembly, a plunger pump assembly, a flow distribution plate, a main shaft and a shell. The servo motor assembly, the plunger pump assembly and the valve plate are sequentially arranged in the axial direction. The left main oil port is communicated with a rod cavity of the asymmetric hydraulic cylinder, the third oil port is communicated with an oil tank, and the right main oil port is communicated with a connecting rodless cavity of the asymmetric hydraulic cylinder; a kidney-shaped groove is machined in the end face, located on the cylinder body matching side, of the right main oil port. A kidney-shaped groove is machined in the end face, located on the cylinder body matching side, of the left main oil port. A kidney-shaped groove is machined in the end face, located on the cylinder body matching side, of the third oil port. A circular counter bore is machined in the end face of the right main oil port on the oil hole side; a circular counter bore is machined in the end face of the left main oil port on the oil hole side; a circular counter bore is machined in the end face, located on the oil hole side, of the third oil port. Only one servo motor pump is adopted, the purpose of controlling the asymmetric hydraulic cylinder can be achieved, and redundant hydraulic devices such as a hydraulic control one-way valve are omitted.

Description

Technical Field

[0001] This invention relates to the field of hydraulic servo system technology, specifically to a servo motor pump with a three-port flow distribution structure. Background Technology

[0002] Servo motor pumps are a core component of emerging electro-hydraulic actuation systems (EHAs), essentially simplifying the traditional three components—motor, hydraulic pump, and servo valve—into one, combining power, energy conversion, and control functions to directly convert adjustable electricity into controllable flow. Currently, integrated solutions commonly employ a coaxial, shared-casing design for the motor and piston pump. The distribution plate 3, a crucial component of the piston pump, relies on the reciprocating motion of the piston within the cylinder to alter the sealed working chamber, thus achieving oil suction and discharge. Early servo motor pumps often used a split structure, later evolving into symmetrical integrated distribution plates. However, the application requirements of asymmetrical hydraulic cylinders necessitate new distribution solutions.

[0003] Currently, integrated servo motor pump products, such as the patent document "A Highly Integrated Oil Internal Circulation Servo Motor Pump" (ZL202110679550.0), use a symmetrical distribution plate structure. However, because the forward and reverse output flow rates are equal, the symmetrical distribution plate generally achieves flow demand distribution by adding a hydraulically controlled check valve, and therefore cannot be directly adapted to asymmetrical hydraulic cylinders.

[0004] The patent document "A Combined Distribution Plate for an Axial Piston Pump with Three Distribution Windows" (ZL202010054024.0) uses a combined distribution plate, which includes a first distribution plate and a second distribution plate with a disc structure. The first distribution plate has symmetrically arranged distribution windows I and II, and the second distribution plate has an annular window corresponding to the first distribution plate. An adjusting slider is used to adjust the area ratio of the distribution windows. The first and second distribution plates are stacked. This structure involves two parts. Although the flow ratio is adjusted by adjusting the slider, the installation and fixing are relatively complex. The complex installation and insufficient dynamic sealing reliability may limit the reliability of the combined distribution plate under high speed and high pressure conditions (such as insufficient dynamic fit accuracy between parts). Summary of the Invention

[0005] The purpose of this invention is to provide a three-port distribution structure servo motor pump. To overcome the limitation that existing servo motor pumps can only be applied to single-rod hydraulic cylinder actuation systems by adding hydraulic components, this invention provides a three-port distribution plate structure that is suitable for application scenarios where the two chambers of the hydraulic cylinder have different working areas (uneven required flow rates). It can achieve energy conversion and also has the characteristics of highly integrated output control.

[0006] The technical solution of this invention is: A three-port distribution structure servo motor pump includes: a servo motor assembly, a plunger pump assembly, a distribution plate, a main shaft, and a housing; The housing contains a plunger pump assembly and a servo motor assembly; The servo motor assembly, plunger pump assembly, and distributor plate are arranged sequentially along the axial direction; The servo motor assembly outputs torque to the piston pump assembly via the spindle; The end face of the distributor plate facing the piston pump assembly serves as the cylinder block mating side, while the other end face of the distributor plate serves as the oil hole side. The distributor plate has a center hole machined on the end face of the cylinder block mating side. The center hole is used to connect the spindle through the bearing. The distribution plate is equipped with a right main oil port, a left main oil port, and a third oil port; The left main oil port connects to the rod chamber of the asymmetric hydraulic cylinder, the third oil port connects to the oil tank, and the right main oil port connects to the rodless chamber of the asymmetric hydraulic cylinder. The right main oil port has a waist-shaped groove machined on the end face of the cylinder block mating side; The left main oil port has a waist-shaped groove machined on the end face of the cylinder block mating side; The end face of the third oil port on the cylinder block mating side is machined with a waist-shaped groove; The right-side main oil port has a circular countersunk hole machined on the end face located on the oil hole side; The left main oil port has a circular countersunk hole machined on the end face of the oil hole side; The end face of the third oil port, located on the side of the oil hole, is machined with a circular countersunk hole.

[0007] Preferably, the diameters of the circular countersunk holes of the right main oil port, the left main oil port, and the third oil port are the same.

[0008] Preferably, the end face of the distribution plate located on the oil hole side is also machined with two intersecting low-pressure oil drain grooves, and oil drain holes that run through the axial direction are machined on the two low-pressure oil drain grooves respectively. The drain hole is used to connect the oil inside the housing to the external oil tank.

[0009] Preferably, an eccentric milled ring groove is machined between the circular countersunk hole and the waist-shaped groove of the main oil port on the right side to increase the oil suction and discharge capacity of the distribution plate. The cross-sectional area of ​​the eccentric milled annular groove is larger than the cross-sectional area of ​​the circular countersunk hole.

[0010] Preferably, the flow rate ratio between the right main oil port and the left main oil port is determined based on the effective area of ​​the rod-side and rodless-side chambers of the hydraulic cylinder.

[0011] Preferably, it further includes: a physical isolation structure; After machining two symmetrically distributed waist-shaped grooves on the cylinder body mating side end face of the distributor plate, a physical isolation structure is fixed between the left main oil port and the third oil port to obtain the waist-shaped groove on the cylinder body mating side end face of the left main oil port and the waist-shaped groove on the cylinder body mating side end face of the third oil port.

[0012] Compared with the prior art, the present invention has at least the following beneficial effects: 1) This invention adopts an integrated servo motor pump and a three-port distribution plate design for servo motor pump products, overcoming the limitation that existing motor pump products can only be applied to symmetrical hydraulic cylinder systems by adding hydraulic components.

[0013] 2) The distribution plate of the present invention has three oil ports: two main oil ports and one auxiliary oil port for balancing flow, which replaces the symmetrical distribution plate structure in the prior art and can be applied to application scenarios where the working areas of the two chambers of the hydraulic cylinder are different (the required flow is unbalanced).

[0014] 3) By adding an eccentric milled ring groove to the bottom of the main oil port groove of the rod cavity, the flow area of ​​the distribution plate of the present invention can be increased, so as to alleviate the flow restriction and hydraulic shock problems caused by the significant reduction of the flow area of ​​the oil port due to the three-port design.

[0015] 4) The present invention designs two or three radially radiating low-pressure oil drain grooves on the oil hole side of the distribution plate, with the center as the starting point. Each groove has an oil drain port at the bottom, which is connected to the low pressure of the system to solve the low-pressure oil drain problem caused by the three-oil-port design. Attached Figure Description

[0016] Figure 1 This is a partial sectional view of a servo motor pump.

[0017] Figure 2 This is a diagram showing the layout of the oil holes on the distribution plate on the oil hole side.

[0018] Figure 3 This is a structural diagram of the oil waist-shaped groove for the cylinder block to fit the side distribution plate.

[0019] Figure 4 This is a partial cross-sectional view of the eccentrically milled oil hole in the distribution plate.

[0020] Figure 5 This is a cross-sectional view of the distribution plate. Detailed Implementation

[0021] This invention discloses a servo motor pump distribution structure design for asymmetric hydraulic cylinders. The servo motor and piston pump are designed as an integrated unit with a common housing and coaxial structure. The distribution plate has a three-port distribution design, which is suitable for electro-static (hydraulic) actuation systems composed of asymmetric hydraulic cylinders.

[0022] To better describe the present invention, the present invention will be described in detail below with reference to schematic diagrams and examples.

[0023] This invention integrates the design of "servo motor + plunger pump" with the design of three-port oil distribution plate, so as to control the asymmetric hydraulic cylinder with the fewest number of components, that is, only one servo motor pump, eliminating the need for redundant hydraulic components such as hydraulic control check valve.

[0024] A three-port distribution structure servo motor pump includes: a servo motor assembly 1, a plunger pump assembly 2, a distribution plate 3, a main shaft 4, a housing 5, a spring retainer 6, and a positioning pin 7. The servo motor transmits the electromagnetic torque to the plunger pump assembly 2 through the main shaft 4, driving the rotating parts to rotate and realizing the normal operation of the plunger pump.

[0025] The housing 5 houses a plunger pump assembly 2 and a servo motor assembly 1. The servo motor assembly 1 outputs torque to the plunger pump assembly 2 via the main shaft 4. Figure 1 As shown, the servo motor assembly 1 is located in the left cavity of the housing 5, the plunger pump assembly 2 is located in the right cavity of the housing 5, and the distribution plate 3 is located to the right of the plunger pump assembly 2. The distribution plate 3 is axially positioned by the spring retainer 6 and radially fixed by the positioning pin 7.

[0026] Distribution plate 3 adopts a three-port design, such as Figure 2 As shown, the distribution plate 3 is provided with a right main oil port 3-1, a left main oil port 3-2, and a third oil port 3-3. The left main oil port 3-2 is connected to the rod chamber of the asymmetric hydraulic cylinder, the third oil port 3-3 is connected to the oil tank, and the right main oil port 3-1 is connected to the rodless chamber of the asymmetric hydraulic cylinder.

[0027] The right main oil port 3-1 is used as the high-pressure main oil port, and the left main oil port 3-2 is used as the low-pressure main oil port.

[0028] The end face of the distributor plate 3 facing the piston pump assembly 2 serves as the cylinder block mating side, and the other end face of the distributor plate 3 serves as the oil hole side.

[0029] The end face of the cylinder block mating side is machined with a center hole 3-10, which is used to connect the spindle 4 through the bearing.

[0030] The right main oil port 3-1 has a waist-shaped groove machined on the end face of the cylinder block mating side; The left main oil port 3-2 has a waist-shaped groove machined on the end face of the cylinder block mating side; The third oil port 3-3 has a waist-shaped groove machined on the end face of the cylinder block mating side; The right main oil port 3-1 has a circular countersunk hole machined on the end face of the oil hole side, and an eccentric milled ring groove 3-9 is machined between the circular countersunk hole and the waist-shaped groove. The left main oil port 3-2 has a circular countersunk hole machined on the end face located on the oil hole side; The end face of the third oil port 3-3 located on the oil hole side is machined with a circular countersunk hole; The diameters of the circular countersunk holes of the right main oil port 3-1, the left main oil port 3-2, and the third oil port 3-3 are the same.

[0031] To facilitate the timely return of oil from the casing to the oil tank, two or three radially radiating grooves originating from the center are designed on the oil hole side of the distribution plate 3 as low-pressure drain grooves 3-5. Each groove has a drain port 3-6 at its bottom. The drain port 3-6 is used to connect the oil inside the casing to the external oil tank, connecting the system's low pressure, thus solving the low-pressure oil leakage problem caused by the three-port design. In one embodiment of the invention, two low-pressure drain grooves 3-5 intersecting at the center point are also machined on the end face of the oil hole side of the distribution plate 3. Each of the two low-pressure drain grooves 3-5 has an axially penetrating drain port 3-6 machined on it. To facilitate the disassembly and assembly of the distribution plate 3, a threaded hole 3-4 is provided at the center, which can also serve as a low-pressure oil drain hole for the housing.

[0032] like Figure 3 The diagram shows the working surface of the distributor plate 3, i.e., the cylinder block mating side. The distributor plate 3 of this invention has an asymmetrical structure. Considering manufacturing costs, two symmetrically distributed waist-shaped distribution windows 3-7 are first machined on the cylinder block mating side of the distributor plate 3. A physical isolation structure 3-8 is fixed between the left main oil port 3-2 and the third oil port 3-3, thereby... Figure 3 The waist-shaped distribution window 3-7 on the left is divided into two waist-shaped slots.

[0033] Oil is supplied to the rod chamber of the hydraulic cylinder via the left main oil port 3-2, while oil is supplied to the rodless chamber via the right main oil port 3-1. The third oil port 3-3 returns excess oil generated when the plunger moves to this position back to the oil tank. Based on the effective areas of the rod and rodless chambers of the hydraulic cylinder, the flow ratio from the right main oil port 3-1 to the left main oil port 3-2 to the hydraulic cylinder is determined to be 2.56:1.

[0034] like Figure 4 , 5 As shown, in order to increase the oil suction and discharge capacity of the distribution plate 3 and expand the oil passage area, an eccentric milled ring groove 3-9 is machined between the circular countersunk hole and the waist-shaped groove. In one embodiment of the present invention, the eccentricity of the eccentric milled ring groove 3-9 is 1.5mm and the groove depth is 7mm, so as to alleviate the flow restriction and hydraulic shock problems caused by the significant reduction of the oil passage area due to the three-oil port design.

[0035] While the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Any person skilled in the art can make possible variations and modifications to the technical solutions of the present invention using the disclosed methods and techniques without departing from the spirit and scope of the invention. Therefore, any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention, without departing from the content of the technical solutions of the present invention, shall fall within the protection scope of the present invention. Where there is no conflict, the embodiments of this application and the technical features thereof can be combined with each other.

[0036] The contents not described in detail in this specification are common knowledge to those skilled in the art.

Claims

1. A servo motor pump with a three-port flow distribution structure, characterized in that, include: Servo motor assembly (1), plunger pump assembly (2), distributor plate (3), spindle (4) and housing (5); The housing (5) contains a plunger pump assembly (2) and a servo motor assembly (1). The servo motor assembly (1), the plunger pump assembly (2), and the distributor plate (3) are arranged sequentially along the axial direction; The servo motor assembly (1) outputs torque to the piston pump assembly (2) through the spindle (4); The end face of the distributor plate (3) facing the piston pump assembly (2) serves as the cylinder block mating side, and the other end face of the distributor plate (3) serves as the oil hole side; The distribution plate (3) has a center hole (3-10) machined on the end face of the cylinder body mating side. The center hole (3-10) is used to connect the spindle (4) through the bearing. The distribution plate (3) is provided with a right main oil port (3-1), a left main oil port (3-2), and a third oil port (3-3). The left main oil port (3-2) connects to the rod chamber of the asymmetric hydraulic cylinder, the third oil port (3-3) connects to the oil tank, and the right main oil port (3-1) connects to the rodless chamber of the asymmetric hydraulic cylinder. The right main oil port (3-1) has a waist-shaped groove machined on the end face of the cylinder block mating side; The left main oil port (3-2) has a waist-shaped groove machined on the end face of the cylinder block mating side; The third oil port (3-3) has a waist-shaped groove machined on the end face of the cylinder block mating side; The right main oil port (3-1) has a circular countersunk hole machined on the end face of the oil hole side; The left main oil port (3-2) has a circular countersunk hole machined on the end face of the oil hole side; The third oil port (3-3) has a circular countersunk hole machined on the end face of the oil hole side.

2. The servo motor pump with a three-port flow distribution structure according to claim 1, characterized in that, The diameters of the circular countersunk holes of the right main oil port (3-1), the left main oil port (3-2), and the third oil port (3-3) are the same.

3. A servo motor pump with a three-port flow distribution structure according to claim 2, characterized in that, Two low-pressure drain grooves (3-5) intersecting at the center are also machined on the end face of the distribution plate (3) located on the oil hole side. Drain holes (3-6) that run through the axial direction are machined on the two low-pressure drain grooves (3-5). The drain hole (3-6) is used to connect the oil inside the housing (5) to the external oil tank.

4. A servo motor pump with a three-port flow distribution structure according to claim 3, characterized in that, An eccentric milled ring groove (3-9) is machined between the circular countersunk hole and the waist-shaped groove of the main oil port (3-1) on the right side to increase the oil suction and discharge capacity of the distribution plate (3); The cross-sectional area of ​​the eccentric milled annular groove (3-9) is larger than the cross-sectional area of ​​the circular countersunk hole.

5. A servo motor pump with a three-port flow distribution structure according to any one of claims 2-4, characterized in that, The flow ratio between the right main oil port (3-1) and the left main oil port (3-2) is determined based on the effective area of ​​the rod-side and rodless-side chambers of the hydraulic cylinder.

6. A servo motor pump with a three-port flow distribution structure according to claim 5, characterized in that, Also includes: Physical isolation structure (3-8); After machining two symmetrically distributed waist-shaped grooves on the cylinder body mating side end face of the distributor plate (3), a physical isolation structure (3-8) is fixed between the two oil ports (3-2 on the left and 3-3 on the right), thereby obtaining the waist-shaped groove on the cylinder body mating side end face of the left main oil port (3-2) and the waist-shaped groove on the cylinder body mating side end face of the third oil port (3-3).

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