Swash plate type axial plunger pump

Abstract

The invention discloses a swash plate type axial plunger pump in the technical field of plunger pumps, which comprises a shell, a control valve and a hydraulic assembly, a swash plate capable of moving obliquely is arranged in the shell, a valve plate is arranged at the rear end of the shell, and a pump oil discharge port and a pump oil suction port are formed in the valve plate; the control valve is embedded in the shell and comprises a valve sleeve and a variable cylinder arranged at the front end of the valve sleeve in a sleeving mode, a first pressure oil port, a second pressure oil port and an oil return port are formed in the side portion of the valve sleeve, a valve element is movably arranged on the inner wall of the valve sleeve, and a third pressure oil port is formed in the variable cylinder. The hydraulic assembly comprises a cylinder body and a piston which are connected in a nested mode, and a fourth pressure oil port is formed in the cylinder body. Wherein the piston and the top of the variable cylinder are oppositely arranged on the two sides of the swash plate, the first pressure oil port is communicated with the pump oil discharge port and the fourth pressure oil port, the second pressure oil port is communicated with the third pressure oil port, and the inner diameter of the cylinder body is smaller than that of the variable cylinder; in the working process of the pump, the variable response time, the control precision and the control and working reliability can be improved.

Description

Technical Field

[0001] The invention relates to the technical field of plunger pumps, and in particular to a swash plate type axial plunger pump. Background Art

[0002] According to the development trend of miniaturization and simplified structure of plunger pumps, smaller plunger pump products have emerged, especially miniaturized designs for variable control mechanisms. Figure 1 As shown, this structure redesigns the control structure of the electronically controlled variable based on the traditional plunger pump constant power control method, redesigns the single variable piston, and controls the oil flow into or out of the piston through the control valve to change the swash plate and change the pump displacement.

[0003] The variable control mechanism of this structure has one side of the swash plate in contact with the variable piston and the other side in contact with the return spring. The return stroke of the swash plate, that is, the process of the swash plate changing from 0 displacement to large displacement, mainly relies on the spring force. The spring force is small and the variable piston area is large, so the pressure after the valve is low. The control mechanism is easily affected by the outlet pressure and the return oil pressure, so the variable response time is long and the variable control stability is poor. At the same time, the spring is prone to deformation after the plunger pump has worked for a long time, which will cause the plunger pump to fail. The internal structure of the control valve with a variable piston is also relatively complex, and it is inconvenient to debug and use. Summary of the invention

[0004] The purpose of the present invention is to overcome the deficiencies in the prior art and to provide a swash plate axial piston pump. The existing small volume piston pumps have the technical problems of long variable response time, poor variable control stability, short service life and inconvenient debugging and use.

[0005] To achieve the above object, the present invention is implemented by adopting the following technical solutions: The present invention provides a swash plate type axial piston pump, comprising: The housing is provided with a tiltable swash plate inside, and a distribution plate is provided at the rear end, and the distribution plate is provided with a pump oil discharge port and a pump oil suction port; A control valve is embedded in the housing, the control valve comprises a valve sleeve and a variable cylinder sleeved on the front end of the valve sleeve, the side of the valve sleeve is provided with a first pressure oil port, a second pressure oil port and an oil return port, a valve core is movably provided on the inner wall of the valve sleeve, the valve core is used to connect the second pressure oil port with the first pressure oil port or the oil return port, and the variable cylinder is provided with a third pressure oil port; A hydraulic assembly, comprising a cylinder body and a piston connected in a nested manner, wherein the cylinder body is provided with a fourth pressure oil port; Among them, the top of the piston and the variable cylinder are relatively arranged on both sides of the swash plate, the first pressure oil port is connected with the pump oil discharge port and the fourth pressure oil port respectively, the second pressure oil port is connected with the third pressure oil port, and the inner diameter of the cylinder body is smaller than the inner diameter of the variable cylinder.

[0006] Optionally, a steel ball is provided on the top of the variable cylinder, a ball groove matching with the steel ball is provided on the swash plate, and the steel ball is embedded in the ball groove to realize the articulation of the variable cylinder and the swash plate.

[0007] Optionally, a protrusion is provided on the swash plate, and the top of the piston abuts against the protrusion.

[0008] Optionally, a screw plug is threadedly connected to the rear end of the valve sleeve, and a driving component for driving the valve core to slide along the inner wall of the valve sleeve is connected to the screw plug.

[0009] Optionally, the driving component adopts a proportional solenoid valve or a pilot oil circuit.

[0010] Optionally, the first pressure oil port, the second pressure oil port and the return oil port are arranged in parallel in sequence, and the outer wall of the valve core is provided with a first groove and a second groove in parallel; when the valve core is in an initial state, the first pressure oil port and the second pressure oil port are connected through the first groove, and when the valve core is in a controlled state, the second pressure oil port and the return oil port are connected through the second groove.

[0011] Optionally, a feedback spring is provided between the valve core and the variable cylinder.

[0012] Optionally, a guide column is provided on the inner wall of the variable cylinder, a column groove is provided on the front end of the valve core, one end of the feedback spring is sleeved on the guide column, and the other end is embedded in the column groove.

[0013] Optionally, a pressure regulating screw is threadedly connected to the front end of the valve sleeve, and a pressure regulating spring is provided between the valve core and the pressure regulating screw.

[0014] Optionally, the pressure regulating screw extends outside the valve sleeve and is provided with a locking nut.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a swash plate axial piston pump, which 1) eliminates the spring-type swash plate return structure in the prior art and uses pressure oil to control the variable piston structure, thereby improving the stability of the pump variable mechanism and the working reliability; the piston and the variable cylinder are both acted upon by the pressure oil, and the force they are subjected to is much greater than the spring force, so that the control pressure is less affected by the housing return oil pressure, greatly improving the pump variable control accuracy and stability. 2) The design of the pressure regulating spring makes the pump variable starting point adjustable, which greatly facilitates product assembly and debugging. The design of the feedback spring makes the pump displacement control closed-loop, which can accurately control the pump displacement. 3) The structure of the control valve is simpler and easy to assemble and use. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a structural schematic diagram of an existing plunger pump provided in the background technology of the present invention; Figure 2 It is a schematic structural diagram of a swash plate axial piston pump provided by an embodiment of the present invention; Figure 3 is a schematic structural diagram of a control valve provided by an embodiment of the present invention; Figure 4 Schematic diagram of the principle of a swash plate axial piston pump provided by an embodiment of the present invention; The markings in the figure are: 1. Housing; 11. Swash plate; 111. Protrusion; 112. Ball groove; 12. Distribution plate; 121. Pump oil discharge port; 122. Pump oil suction port; 2. Control valve; 21. Valve sleeve; 211. First pressure oil port; 212. Second pressure oil port; 213. Oil return port; 22. Variable cylinder; 221. Third pressure oil port; 222. Steel ball; 23. Valve core; 231. First groove; 232. Second groove; 24. Screw plug; 25. Feedback spring; 251. Guide column; 252. Column groove; 26. Pressure regulating screw; 27. Locking nut; 28. Pressure regulating spring; 3. Hydraulic assembly; 31. Cylinder body; 311. Fourth pressure oil port; 32. Piston. DETAILED DESCRIPTION

[0017] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present invention.

[0018] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and the like are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", and the like may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more. In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood by specific circumstances.

[0019] Embodiment 1:

[0020] like Figure 2 As shown, an embodiment of the present invention provides a swash plate type axial piston pump, including a housing 1, a control valve 2 and a hydraulic assembly 3. A tiltable swash plate 11 is provided in the housing 1, a valve plate 12 is provided at the rear end, and a pump oil discharge port 121 and a pump oil suction port 122 are provided on the valve plate 12; the swash plate 11 is usually fixed by an arc-shaped track, and the main axis direction of the piston pump is taken as the horizontal direction. The swash plate 11 can be tilted along the arc-shaped track at an angle of 0-20° with the vertical direction. The pump oil discharge port 121 and the pump oil suction port 122 are usually two waist-shaped grooves arranged symmetrically.

[0021] The control valve 2 is embedded in the housing 1. The control valve 2 includes a valve sleeve 21 and a variable cylinder 22 sleeved on the front end of the valve sleeve 21. The side of the valve sleeve 21 is provided with a first pressure oil port 211, a second pressure oil port 212 and an oil return port 213. The inner wall of the valve sleeve 21 is movably provided with a valve core 23. The valve core 23 is used to connect the second pressure oil port 212 with the first pressure oil port 211 or the oil return port 213. The variable cylinder 22 is provided with a third pressure oil port 221. Figure 3As shown, the specific structure is as follows: the first pressure oil port 211, the second pressure oil port 212 and the return oil port 213 are arranged in parallel in sequence, and the outer wall of the valve core 23 is provided with a first groove 231 and a second groove 232 in parallel; when the valve core 23 is in the initial state, the first pressure oil port 211 and the second pressure oil port 212 are connected through the first groove 231, and when the valve core 23 is in the controlled state, the second pressure oil port 212 and the return oil port 213 are connected through the second groove 232.

[0022] The rear end of the valve sleeve 21 is threadedly connected with a screw plug 24, and the screw plug 24 is connected with a driving component for driving the valve core 23 to slide along the inner wall of the valve sleeve 21. The driving component adopts a proportional solenoid valve or a pilot oil circuit, and provides a working driving force for the valve core 23 through the driving component.

[0023] The hydraulic assembly 3 includes a cylinder body 31 and a piston 32 which are nested and connected. The cylinder body 31 is provided with a fourth pressure oil port 311. The tops of the piston 32 and the variable cylinder 22 are relatively arranged on both sides of the swash plate 11. The specific structure is as follows: a steel ball 222 is arranged on the top of the variable cylinder 22, and a ball groove 112 which matches the steel ball 222 is arranged on the swash plate 11. The steel ball 222 is embedded in the ball groove 112 to realize the articulation of the variable cylinder 22 and the swash plate 11. A protrusion 111 is arranged on the swash plate 11, and the top of the piston 32 abuts against the protrusion 111. With the main axis direction of the plunger pump as the horizontal direction, the piston 32 is arranged horizontally, and the variable cylinder 22 forms an angle of 15-30° with the horizontal direction.

[0024] like Figure 4 As shown, the oil circuit connection relationship of this embodiment is: the first pressure oil port 211 is connected to the pump oil discharge port 121 and the fourth pressure oil port 311 respectively, the second pressure oil port 212 is connected to the third pressure oil port 221, and the inner diameter of the cylinder body 31 is smaller than the inner diameter of the variable cylinder 22. Its working principle is: The plunger pump is a flow-positive control pump, that is, the input signal is proportional to the pump's displacement. At the beginning of the operation, the plunger pump is in a 0 displacement state. As the input signal increases, the pump changes to a large displacement.

[0025] When the pump starts working, the outlet pressure oil enters the cylinder body 31 through the pump discharge port 121, the first pressure oil port 211, and the fourth pressure oil port 311. At this time, the piston 32 pushes the swash plate 11 to a large angle; the valve core 23 is in the initial state, the first pressure oil port 211 and the second pressure oil port 212 are connected through the first groove 231, and the outlet pressure oil enters the variable cylinder 22 through the pump discharge port 121, the first pressure oil port 211, and the second pressure oil port 212 at the same time. At this time, the variable cylinder 22 pushes the swash plate 11 to a small angle. Since the force area of ​​the variable cylinder 22 is larger than the force area of ​​the piston 32, the force of the variable cylinder 22 is larger than the force of the piston 32. Therefore, when the pump starts, under the action of the pressure oil at the pump discharge port 121, the swash plate 11 is pushed to 0 angle, that is, the pump is at 0 displacement.

[0026] When the valve core 23 enters the controlled state under the action of the driving component, the first pressure oil port 211 and the second pressure oil port 212 are gradually disconnected, and the second pressure oil port 212 and the return oil port 213 are gradually connected. The pressure oil of the variable cylinder 22 enters the pump suction port 122 through the second pressure oil port 212 and the return oil port 213. The force of the variable cylinder 22 gradually decreases and is less than the force of the piston 32. The angle of the swash plate 11 gradually increases, causing the pump displacement to change to a large displacement.

[0027] In addition, a feedback spring 25 is provided between the valve core 23 and the variable cylinder 22. The specific structure is as follows: a guide column 251 is provided on the inner wall of the variable cylinder 22, a column groove 252 is provided at the front end of the valve core 23, one end of the feedback spring 25 is sleeved on the guide column 251, and the other end is embedded in the column groove 252. The feedback spring 25 can be stabilized by the guide column 251 and the column groove 252, so that its working state is stable.

[0028] Since the variable cylinder 22 exerts force on one end of the feedback spring 25 and the valve core 23 exerts force on the other end, the movement of the variable cylinder 22 and the valve core 23 will cause the elastic force of the feedback spring 25 to change. When the valve core 23 moves to the left under the drive of the driving component, the thrust on the right side of the feedback spring 25 is greater than that on the left side; at this time, the swash plate 11 rotates to a large angle, and the variable cylinder 22 moves to the right until the force on the right side of the feedback spring 25 is balanced with the force on the left side, the valve core 23 stops moving, the pump displacement is changed, and the closed-loop control of the pump displacement control is completed. The input signal is positively correlated with the pump displacement and corresponds one to one, so the pump displacement can be accurately controlled.

[0029] In addition, a pressure regulating screw 26 is threadedly connected to the front end of the valve sleeve 21 , a pressure regulating spring 28 is provided between the valve core 23 and the pressure regulating screw 26 , and the pressure regulating screw 26 extends to the outside of the valve sleeve 21 and is provided with a locking nut 27 .

[0030] When the variable starting point needs to be adjusted, the valve sleeve 21 is removed, the pressure regulating screw 26 is rotated, and the preload force of the pressure regulating spring 28 is changed to change the pump variable displacement starting point. Compared with the previous use of adjusting gaskets to adjust the variable starting point, this design is simple in structure, convenient and fast.

[0031] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A swash plate axial piston pump, characterized in that: include: The housing is provided with a tiltable swash plate inside, and a distribution plate is provided at the rear end, and the distribution plate is provided with a pump oil discharge port and a pump oil suction port; A control valve is embedded in the housing, the control valve comprises a valve sleeve and a variable cylinder sleeved on the front end of the valve sleeve, the side of the valve sleeve is provided with a first pressure oil port, a second pressure oil port and an oil return port, a valve core is movably provided on the inner wall of the valve sleeve, the valve core is used to connect the second pressure oil port with the first pressure oil port or the oil return port, and the variable cylinder is provided with a third pressure oil port; A hydraulic assembly, comprising a cylinder body and a piston connected in a nested manner, wherein the cylinder body is provided with a fourth pressure oil port; Among them, the top of the piston and the variable cylinder are relatively arranged on both sides of the swash plate, the first pressure oil port is connected with the pump oil discharge port and the fourth pressure oil port respectively, the second pressure oil port is connected with the third pressure oil port, and the inner diameter of the cylinder body is smaller than the inner diameter of the variable cylinder.

2. The swash plate type axial piston pump according to claim 1, characterized in that: A steel ball is arranged on the top of the variable cylinder, a ball groove matched with the steel ball is arranged on the swash plate, and the steel ball is embedded in the ball groove to realize the hinge connection between the variable cylinder and the swash plate.

3. The swash plate type axial piston pump according to claim 1, characterized in that: The swash plate is provided with a protrusion, and the piston top abuts against the protrusion.

4. The swash plate type axial piston pump according to claim 1, characterized in that: The rear end of the valve sleeve is threadedly connected with a screw plug, and the screw plug is connected with a driving component for driving the valve core to slide along the inner wall of the valve sleeve.

5. The swash plate type axial piston pump according to claim 4, characterized in that: The driving component adopts a proportional solenoid valve or a pilot oil circuit.

6. The swash plate type axial piston pump according to claim 1, characterized in that: The first pressure oil port, the second pressure oil port and the return oil port are arranged in parallel in sequence, and the outer wall of the valve core is provided with a first groove and a second groove in parallel; when the valve core is in an initial state, the first pressure oil port and the second pressure oil port are connected through the first groove, and when the valve core is in a controlled state, the second pressure oil port and the return oil port are connected through the second groove.

7. The swash plate type axial piston pump according to claim 1, characterized in that: A feedback spring is provided between the valve core and the variable cylinder.

8. The swash plate type axial piston pump according to claim 7, characterized in that: A guide column is arranged on the inner wall of the variable cylinder, a column groove is arranged at the front end of the valve core, one end of the feedback spring is sleeved on the guide column, and the other end is embedded in the column groove.

9. The swash plate type axial piston pump according to claim 1, characterized in that: The front end of the valve sleeve is threadedly connected with a pressure regulating screw, and a pressure regulating spring is arranged between the valve core and the pressure regulating screw.

10. The swash plate type axial piston pump according to claim 9, characterized in that: The pressure regulating screw extends outside the valve sleeve and is provided with a locking nut.

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