A closed hydraulic linear actuator

Abstract

The invention discloses a closed hydraulic linear actuator, comprising: a hydraulic cylinder and a driving device, wherein a moving cavity is provided inside the hydraulic cylinder, the moving cavity is filled with hydraulic oil, a piston moving part is slidably connected inside the moving cavity, the piston moving part comprises a piston moving head and a rod-shaped connecting part, one end of the rod-shaped connecting part passes through the upper end surface of the hydraulic cylinder and extends to the outside, the piston moving head slides against the inner side wall of the hydraulic cylinder; the piston moving head divides the moving cavity into a first cavity and a second cavity; a reserved space is sandwiched between the inner side wall and the outer side wall of the hydraulic cylinder; an air cavity is provided inside the rod-shaped connecting part; a pump group is connected to the driving output end of the driving device; the pump group is provided with a first connecting port and a second connecting port, the first connecting port is connected to the second cavity, the second connecting port is connected to the reserved space, the reserved space is connected to the first cavity, and the first cavity is also connected to the air cavity. The invention improves the compactness of the hydraulic linear actuator structure.

Description

Technical Field

[0001] The present invention relates to the technical field, and in particular to a closed hydraulic linear drive. Background Art

[0002] The traditional hydraulic drive system consists of three parts, including the drive rod, hydraulic oil pump and oil barrel. The hydraulic oil pump consists of four parts: pump body, rectangular oil tank, pressure handle, and ultra-high pressure steel wire braided hose. It is the power element of the hydraulic system, and its function is to convert the mechanical energy of the prime mover into the pressure energy of the liquid. It refers to the oil pump in the hydraulic system, which provides power to the entire hydraulic drive system. When the hydraulic oil pump starts running, it pumps liquid into or extracts liquid into the drive rod, causing the piston rod inside the drive rod to move back and forth, causing the space inside the oil cylinder of the drive rod to change continuously, and an external oil barrel is needed to receive the liquid discharged from the oil cylinder. Therefore, the traditional fixed hydraulic drive system has the defects of large size and low compactness. Summary of the invention

[0003] In view of the deficiencies in the prior art, an object of the present invention is to provide a closed hydraulic linear actuator, which is used to reduce the volume of the hydraulic linear actuator and improve the structural compactness of the hydraulic linear actuator.

[0004] To achieve the above object, the present invention provides the following technical solution: a closed hydraulic linear actuator, comprising:

[0005] A hydraulic cylinder and a driving device, wherein a moving cavity is provided inside the hydraulic cylinder, the moving cavity is filled with hydraulic oil, a piston moving part is slidably connected in the moving cavity, the piston moving part comprises a piston moving head and a rod-shaped connecting part, the piston moving head is fixedly connected to the rod-shaped connecting part, one end of the rod-shaped connecting part away from the piston moving head penetrates the upper end surface of the hydraulic cylinder and extends to the outside, and the piston moving head slides against the inner side wall of the hydraulic cylinder;

[0006] The piston movement head divides the movement cavity into a first cavity and a second cavity, and the first cavity is located above the second cavity;

[0007] A reserved space is provided between the inner wall and the outer wall of the hydraulic cylinder body;

[0008] An air cavity is provided inside the rod-shaped connecting part, and the air cavity is filled with air;

[0009] The driving device is arranged at the lower end of the hydraulic cylinder body, the driving output end of the driving device is connected to a pump group, and the driving device is used to drive the pump group to operate;

[0010] The pump assembly is provided with a first communication port and a second communication port, the first communication port is connected to the second cavity, the second communication port is connected to the reserved space, the reserved space is connected to the first cavity, and the first cavity is also connected to the air cavity;

[0011] When the driving device runs in the forward direction, the pump group pumps the hydraulic oil in the first cavity into the second cavity, driving the piston moving part to move vertically upward.

[0012] Further, the pump group is a gear pump, which includes a pump housing, the first connecting port and the second connecting port are respectively opened on both sides of the pump housing, a first rotating cavity and a second rotating cavity are provided inside the pump housing, the first rotating cavity is connected to the second rotating cavity, a driving gear is rotatably provided in the first rotating cavity, a driven gear is rotatably provided in the second rotating cavity, and the driving gear meshes with the driven gear.

[0013] Furthermore, the driving device is a driving motor, the output shaft of the driving motor passes through the pump body and extends into the first rotating cavity, and the driving gear is sleeved on the output shaft of the driving motor.

[0014] Furthermore, a support seat is fixedly provided at the lower end of the hydraulic cylinder body, an upper end surface of the support seat is in close contact with a lower end surface of the hydraulic cylinder body, and the gear pump is fixedly mounted inside the support seat.

[0015] Furthermore, the piston moving part is a piston rod.

[0016] Furthermore, the reserved space is a sandwich layer, and the shape of the sandwich layer is adapted to the shape of the hydraulic cylinder body.

[0017] Furthermore, a transmission pipeline is provided between the second communication port and the reserved space, and the second communication port is connected to the reserved space through the transmission pipeline.

[0018] Furthermore, a first through hole is penetrated through the lower end surface of the hydraulic cavity, and the second cavity is connected to the first communication port through the first through hole.

[0019] Furthermore, at least one second through hole is provided between the inner side wall of the hydraulic cylinder body and the reserved space, and the reserved space is connected to the first cavity through the second through hole.

[0020] Furthermore, at least one third through hole is provided between the side wall of the rod-shaped connecting portion and the air cavity, and the air cavity is connected to the first cavity through the third through hole.

[0021] Beneficial effects of the present invention:

[0022] The present invention sets a reserved space between the inner wall and the outer wall of the hydraulic cylinder body, and sets an air cavity inside the rod-shaped connecting part, so that when the driving device drives the pump group to extract the hydraulic oil in the first cavity or the second cavity through the reserved space, the hydraulic oil can be pumped into or discharged from the air cavity of the rod-shaped connecting part to offset the volume change of the moving cavity inside the hydraulic cylinder body, and there is no need to set up an oil barrel to discharge or pump in the hydraulic oil, thereby improving the structural compactness of the hydraulic linear drive, reducing the overall volume of the hydraulic linear drive, and realizing a high degree of integration of the hydraulic linear drive; at the same time, the hydraulic linear drive is sealed from the external environment to avoid the external environment from having an adverse effect on the internal structure of the hydraulic linear drive. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is an internal cross-sectional view of the present invention;

[0024] Figure 2 It is a schematic diagram of the external structure of the present invention.

[0025] Figure numerals: 1. Hydraulic cylinder body; 11. First cavity; 12. Second cavity; 13. Reserved space; 14. First through hole; 15. Second through hole; 16. Third through hole; 2. Driving device; 3. Piston moving part; 31. Piston moving head; 32. Rod-shaped connecting part; 33. Air cavity; 4. Pump group; 41. First connecting port; 42. Second connecting port; 43. Transmission pipeline; 5. Support seat. DETAILED DESCRIPTION

[0026] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. The same parts are represented by the same reference numerals. It should be noted that the words "front", "rear", "left", "right", "upper" and "lower" used in the following description refer to directions in the accompanying drawings, and the words "bottom surface" and "top surface", "inner" and "outer" refer to directions toward or away from the geometric center of a specific component, respectively.

[0027] like Figure 1 and Figure 2 As shown, a closed hydraulic linear actuator of this embodiment includes:

[0028] A hydraulic cylinder body 1 and a driving device 2, wherein a moving cavity is provided inside the hydraulic cylinder body 1, the moving cavity is filled with hydraulic oil, a piston moving part 3 is slidably connected in the moving cavity, the piston moving part 3 comprises a piston moving head 31 and a rod-shaped connecting part 32, the piston moving head 31 is fixedly connected to the rod-shaped connecting part 32, one end of the rod-shaped connecting part 32 away from the piston moving head 31 penetrates the upper end surface of the hydraulic cylinder body 1 and extends to the outside, and the piston moving head 31 slides against the inner side wall of the hydraulic cylinder body 1;

[0029] The piston moving head 31 divides the moving cavity into a first cavity 11 and a second cavity 12, and the first cavity 11 is located above the second cavity 12;

[0030] A reserved space 13 is sandwiched between the inner wall and the outer wall of the hydraulic cylinder body 1;

[0031] An air cavity 33 is provided inside the rod-shaped connecting portion 32, and the air cavity 33 is filled with air;

[0032] The driving device 2 is arranged at the lower end of the hydraulic cylinder body 1, and the driving output end of the driving device 2 is connected to the pump group 4, and the driving device 2 is used to drive the pump group 4 to operate;

[0033] The pump group 4 is provided with a first communication port 41 and a second communication port 42. The first communication port 41 is connected to the second cavity 12, and the second communication port 42 is connected to the reserved space 13. The reserved space 13 is connected to the first cavity 11, and the first cavity 11 is also connected to the air cavity 33.

[0034] When the driving device 2 runs in the forward direction, the pump group 4 pumps the hydraulic oil in the first cavity 11 into the second cavity 12, driving the piston moving member 3 to move vertically upward.

[0035] The technical solution sets a reserved space 13 between the inner wall and the outer wall of the hydraulic cylinder body 1, and sets an air cavity 33 inside the rod-shaped connecting part 32, so that when the driving device 2 drives the pump group 4 to extract the hydraulic oil in the first cavity 11 or the second cavity 12 through the reserved space 13, the hydraulic oil can be pumped into or discharged from the air cavity 33 of the rod-shaped connecting part 32 to offset the volume change of the moving cavity inside the hydraulic cylinder body 1, and there is no need to set up an oil barrel to discharge or pump in the hydraulic oil, thereby improving the structural compactness of the hydraulic linear drive, reducing the overall volume of the hydraulic linear drive, and realizing a high degree of integration of the hydraulic linear drive; at the same time, the hydraulic linear drive is sealed from the external environment to avoid the external environment from causing adverse effects on the internal structure of the hydraulic linear drive.

[0036] In a preferred embodiment, the closed hydraulic linear drive is applied to a dental chair to achieve cushioning of the dental chair. The rod-shaped connecting portion 32 of the closed hydraulic linear drive is fixedly connected to the seat of the dental chair. When the patient sits on the dental chair, the rod-shaped connecting portion 32 of the closed hydraulic linear drive is subjected to the vertical downward gravity, and the drive device 2 runs forward, driving the pump group 4 to extract the hydraulic oil in the first cavity 11 into the second cavity 12 through the reserved space 13. At this time, the hydraulic pressure of the second cavity 12 becomes larger, and the hydraulic pressure of the first cavity 11 becomes smaller. Under the action of the hydraulic pressure, the piston moving head 31 is driven to move upward. Therefore, the piston moving part 3 gives the seat a vertical upward thrust to offset part of the patient's gravity on the seat, slow down the seat's descending speed, and thus achieve effective cushioning of the dental chair.

[0037] Preferably, the pump group 4 is a gear pump, which includes a pump casing, a first connecting port 41 and a second connecting port 42 respectively opened on both sides of the pump casing, a first rotating cavity and a second rotating cavity are provided inside the pump casing, the first rotating cavity is connected to the second rotating cavity, a driving gear is rotatably provided in the first rotating cavity, a driven gear is rotatably provided in the second rotating cavity, and the driving gear meshes with the driven gear.

[0038] Preferably, the driving device 2 is a driving motor, the output shaft of the driving motor passes through the pump body and extends into the first rotating cavity, and the driving gear is sleeved on the output shaft of the driving motor. When the driving motor is running, the output shaft of the driving motor drives the driving gear to rotate, and the driving gear drives the driven gear to rotate, and the hydraulic pressure inside the first rotating cavity and the second rotating cavity changes. When the driving motor rotates forward, the driving gear and the driven gear rotate forward, so that the hydraulic pressure at the second connecting port 42 is reduced, and then the hydraulic oil in the reserved space 13 is pumped into the pump housing, and discharged from the second connecting port 42, and flows into the second cavity 12. When the driving motor is reversed, the driving gear and the driven gear rotate in the opposite direction, so that the hydraulic pressure at the first connecting port 41 is reduced, and then the hydraulic oil in the second cavity 12 is pumped into the pump housing, and discharged from the first connecting port 41, flows into the reserved space 13, and is discharged from the reserved space 13 into the first cavity 11, and finally discharged from the first cavity 11 into the air cavity 33.

[0039] Preferably, a support seat 5 is fixedly provided at the lower end of the hydraulic cylinder body 1, the upper end surface of the support seat 5 is fitted against the lower end surface of the hydraulic cylinder body 1, and the gear pump is fixedly mounted inside the support seat 5. By providing the support seat 5, effective support for the hydraulic cylinder body 1 is achieved, and the gear pump is fixed at the same time, thereby improving the structural stability of the technical solution.

[0040] Preferably, the piston moving part 3 is a piston rod.

[0041] Preferably, the reserved space 13 is a sandwich, and the shape of the sandwich is adapted to the shape of the hydraulic cylinder body 1. Further, the reserved space 13 can also be a drilled hole or a milled groove between the inner wall and the outer wall of the hydraulic cylinder body 1.

[0042] Preferably, a transmission pipe 43 is provided between the second communication port 42 and the reserved space 13 , and the second communication port 42 is connected to the reserved space 13 through the transmission pipe 43 .

[0043] Preferably, a first through hole 14 is provided through the lower end surface of the hydraulic cavity, and the second cavity 12 is connected to the first communication port 41 through the first through hole 14. In this embodiment, two first through holes 14 are provided.

[0044] Preferably, at least one second through hole 15 is provided between the inner wall of the hydraulic cylinder body 1 and the reserved space 13, and the reserved space 13 is connected to the first cavity 11 through the second through hole 15. In this embodiment, two second through holes 15 are provided.

[0045] Preferably, at least one third through hole 16 is provided between the side wall of the rod-shaped connecting portion 32 and the air cavity 33, and the air cavity 33 is connected to the first cavity 11 through the third through hole 16. In this embodiment, two third through holes 16 are provided.

[0046] Working principle:

[0047] The hydraulic oil circulation between the first cavity 11 and the second cavity 12 is driven by the operation of the driving device 2. When the driving device 2 is not running, the hydraulic oil between the first cavity 11 and the second cavity 12 cannot circulate, so the rod-shaped connecting part 32 of the piston moving part 3 cannot move up and down under the action of the hydraulic pressure.

[0048] When the rod-shaped connecting portion 32 of the piston moving part 3 is subjected to vertical downward pressure, the driving device 2 runs forward, driving the pump group 4 to extract the hydraulic oil in the first cavity 11 into the second cavity 12 through the reserved space 13. At this time, the hydraulic pressure of the second cavity 12 increases, and the hydraulic pressure of the first cavity 11 decreases. Under the action of the hydraulic pressure, the piston moving head 31 is driven to move upward; at this time, the rod-shaped connecting portion 32 connected to the piston moving head 31 is gradually pushed out of the active cavity, and the internal space of the active cavity gradually increases. At this time, part of the hydraulic oil in the active cavity is discharged from the air cavity 33 into the first cavity 11. At this time, a part of the volume of the air cavity 33 originally occupied by the hydraulic oil is released, so that the air pressure in the air cavity 33 is reduced.

[0049] When the rod-shaped connecting portion 32 of the piston moving part 3 is subjected to a vertical upward pulling force, the driving device 2 runs in the reverse direction, driving the pump group 4 to extract the hydraulic oil in the second cavity 12 into the first cavity 11 through the reserved space 13. At this time, the hydraulic pressure of the first cavity 11 increases, and the hydraulic pressure of the second cavity 12 decreases. Under the action of the hydraulic pressure, the piston moving head 31 is driven to move downward; at this time, the rod-shaped connecting portion 32 connected to the piston moving head 31 is gradually pushed into the active cavity, and the internal space of the active cavity is gradually occupied by the pushed rod-shaped connecting portion 32, while the internal volume of the active cavity remains unchanged. Therefore, part of the hydraulic oil in the active cavity is forced to be pressed into the air cavity 33. At this time, a part of the volume of the air cavity 33 is occupied by the hydraulic oil, so that the air cavity 33 is forced to be compressed by the original air volume, so that the air pressure in the air cavity 33 increases.

[0050] The above are only preferred embodiments of the present invention. The protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A closed hydraulic linear actuator, characterized in that: The invention comprises a hydraulic cylinder body (1) and a driving device (2), wherein a moving cavity is provided inside the hydraulic cylinder body (1), wherein the moving cavity is filled with hydraulic oil, wherein a piston moving part (3) is slidably connected inside the moving cavity, wherein the piston moving part (3) comprises a piston moving head (31) and a rod-shaped connecting part (32), wherein the piston moving head (31) is fixedly connected to the rod-shaped connecting part (32), wherein one end of the rod-shaped connecting part (32) away from the piston moving head (31) penetrates the upper end surface of the hydraulic cylinder body (1) and extends to the outside, and the piston moving head (31) slides against the inner wall of the hydraulic cylinder body (1); The piston moving head (31) divides the moving cavity into a first cavity (11) and a second cavity (12), wherein the first cavity (11) is located above the second cavity (12); A reserved space (13) is provided between the inner wall and the outer wall of the hydraulic cylinder body (1); An air cavity (33) is provided inside the rod-shaped connecting portion (32), and the air cavity (33) is filled with air; The driving device (2) is arranged at the lower end of the hydraulic cylinder body (1), the driving output end of the driving device (2) is connected to a pump group (4), and the driving device (2) is used to drive the pump group (4) to operate; The pump assembly (4) is provided with a first communication port (41) and a second communication port (42), the first communication port (41) being connected to the second cavity (12), the second communication port (42) being connected to the reserved space (13), the reserved space (13) being connected to the first cavity (11), and the first cavity (11) being connected to the air cavity (33); When the driving device (2) runs in the forward direction, the pump group (4) pumps the hydraulic oil in the first cavity (11) into the second cavity (12), driving the piston moving part (3) to move vertically upward; A transmission pipe (43) is provided between the second communication port (42) and the reserved space (13), and the second communication port (42) is connected to the reserved space (13) through the transmission pipe (43); A first through hole (14) is provided through the lower end surface of the hydraulic cavity, and the second cavity (12) is connected to the first communication port (41) through the first through hole (14); At least one second through hole (15) is provided between the inner wall of the hydraulic cylinder body (1) and the reserved space (13), and the reserved space (13) is connected to the first cavity (11) through the second through hole (15); At least one third through hole (16) is provided between the side wall of the rod-shaped connecting portion (32) and the air cavity (33), and the air cavity (33) is connected to the first cavity (11) through the third through hole (16).

2. The closed hydraulic linear actuator according to claim 1, characterized in that: The pump group (4) is a gear pump, which comprises a pump housing, wherein the first communication port (41) and the second communication port (42) are respectively provided on both sides of the pump housing, and a first rotating cavity and a second rotating cavity are provided inside the pump housing, wherein the first rotating cavity is connected to the second rotating cavity, a driving gear is rotatably provided in the first rotating cavity, and a driven gear is rotatably provided in the second rotating cavity, and the driving gear meshes with the driven gear.

3. The closed hydraulic linear actuator according to claim 2, characterized in that: The driving device (2) is a driving motor, the output shaft of the driving motor passes through the pump body and extends into the first rotating cavity, and the driving gear is sleeved on the output shaft of the driving motor.

4. The closed hydraulic linear actuator according to claim 3, characterized in that: A support seat (5) is fixedly provided at the lower end of the hydraulic cylinder body (1); the upper end surface of the support seat (5) is in close contact with the lower end surface of the hydraulic cylinder body (1); and the gear pump is fixedly mounted inside the support seat (5).

5. The closed hydraulic linear actuator according to claim 1, characterized in that: The piston moving part (3) is a piston rod.

6. The closed hydraulic linear actuator according to claim 1, characterized in that: The reserved space (13) is a sandwich layer, and the shape of the sandwich layer is compatible with the shape of the hydraulic cylinder body (1).

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