Piston stroke control mechanism, variable pump and hydraulic reversing valve

Abstract

The utility model relates to a piston stroke control mechanism which comprises a valve body, a piston and a rotating shaft, a piston cavity is arranged in the valve body, the piston is arranged in the piston cavity and can move axially, the piston cavity comprises an upper pressure cavity located at the upper end of the piston, and a thrust mechanism enabling the piston to move upwards is arranged below the piston. The rotating shaft extends into the upper pressure cavity and can rotate around the axis; the rotating shaft can move up and down along with the piston in the axis direction, a transition conversion shaft is fixed to the upper portion of the upper pressure cavity, an inflow channel and a backflow channel are formed in the transition conversion shaft, the rotating shaft is arranged on the transition conversion shaft in a penetrating mode, and an inclined groove communicated with the upper pressure cavity is formed in the peripheral wall of the rotating shaft; the rotation of the rotating shaft enables the chute to be communicated with one of the inflow channel and the backflow channel, or enables the chute to be blocked from both the inflow channel and the backflow channel. The device has the advantages of being reasonable in structure, good in dynamic response characteristic, convenient to control, beneficial to machining and lower in assembly precision requirement.

Description

Technical Field

[0001] The utility model belongs to the field of fluid transmission and control, and in particular relates to a piston stroke control mechanism. The utility model also relates to a variable pump and a hydraulic reversing valve using the piston stroke control mechanism. Background Art

[0002] Various valves (such as reversing valves) and variable pumps are widely used in the hydraulic and pneumatic transmission industry. One of the cores of reversing valves and variable pumps is the valve core (also called piston) stroke control mechanism. For many years, the reversing valve has used the thrust generated by the electromagnetic coil after being energized to drive the valve core of the reversing valve to move, so as to achieve hydraulic or pneumatic reversing, thereby changing the running direction of the hydraulic or pneumatic actuator. The existing electromagnetic reversing valve has the following disadvantages: 1. The reversing of the electromagnetic valve requires electromagnetic force to push all the time, and the valve core will reset when the power is off, but in some occasions, it is necessary to keep the pressure all the time. At this time, the reversing valve needs to be kept in the reversing state all the time. The electromagnetic coil will generate heat and power consumption when it is energized for a long time, and the life of the coil will be greatly shortened. 2. The electromagnetic coil can only push the valve core with a small diameter. The valve core with a large diameter needs to be pushed by the electromagnetic valve to control the hydraulic fluid to push the valve core. This is called an electro-hydraulic reversing valve. Due to the two-stage conversion, the response time of the reversing valve is prolonged. 3. Ordinary electromagnetic valves or electro-hydraulic reversing valves only have several states: open, closed and reversing, and cannot realize the control of the opening size, and the scope of application is limited.

[0003] To this end, the applicant invented the Chinese invention patent "A Piston Stroke Control Mechanism and Variable Pump" with application number ZL202210611343.6 (publication number CN117189538A), which discloses such a piston stroke control mechanism, including a valve body and a piston, a piston cavity is provided in the valve body, the piston is arranged in the piston cavity and can move axially, and the piston cavity includes an upper pressure cavity located at the upper end of the piston; the piston is provided with a pressure oil port and an oil return port, and also includes a rotating shaft extending into the upper pressure cavity and inserted into the piston, and a slanted groove that is always connected to the upper pressure cavity is provided on the peripheral wall of the rotating shaft; the rotation of the rotating shaft can make the slanted groove communicate with one of the pressure oil port and the oil return port so that the piston moves up or down, and when the pressure oil port and the oil return port are blocked by the slanted groove, the piston stops moving. It also includes a thrust mechanism that acts on the piston to enable it to move upward. The thrust mechanism is a lower pressure cavity located at the lower end of the piston, and the lower pressure cavity is connected to the oil inlet of the valve body. The piston has a connecting flow channel for connecting the pressure oil port and the lower pressure chamber. The area of ​​the upper force-bearing surface of the piston acted on by the pressure oil in the upper pressure chamber is larger than the area of ​​the lower force-bearing surface of the piston acted on by the pressure oil in the lower pressure chamber.

[0004] The aforementioned patent has the following defects: it is very difficult to process a long and slender connecting flow channel in the piston, and the production efficiency is low and the production cost is high; the rotating shaft in the aforementioned patent must not only rotate around its own axis relative to the piston, but also move relative to the axis of the rotating shaft. The rotating shaft, the driving shaft that drives the rotating shaft to rotate, the upper pressure chamber and the piston require mutual concentric cooperation among the four, and the cumulative tolerance is quite large, making it difficult to process and grasp the concentricity. If the concentricity is not good, the friction loss between the rotating shaft and the piston is large, the friction force increases, the life is short, and it will bring additional friction. The piston may drive the rotating shaft to move up and down, thereby affecting the stability of the product and the failure rate is high. Therefore, the assembly accuracy requirements between the four are very high, and the qualified rate of the product will be greatly reduced. In summary, the existing piston stroke control mechanism for valves and variable pumps needs to be further improved. Utility Model Content

[0005] The first technical problem to be solved by the utility model is to provide a piston stroke control mechanism with a reasonable structure, good dynamic response characteristics, convenient control, and conducive to processing and lower assembly precision requirements in response to the above-mentioned existing technical status.

[0006] The technical solution adopted by the utility model to solve the above-mentioned first technical problem is: a piston stroke control mechanism, including a valve body, a piston, and a rotating shaft. The valve body is provided with a piston chamber, the piston is arranged in the piston chamber and can move axially, the piston chamber includes an upper pressure chamber located at the upper end of the piston, a thrust mechanism is provided below the piston to enable it to move upward, the rotating shaft extends into the upper pressure chamber and can rotate around its own axis; the rotating shaft can also move up and down along the axial direction with the piston, a transition conversion shaft is fixed above the upper pressure chamber, the transition conversion shaft is provided with an inlet channel and a reflux channel, the rotating shaft is penetrated by the transition conversion shaft, and an inclined groove connected to the upper pressure chamber is provided on the outer peripheral wall of the rotating shaft; the rotation of the rotating shaft can make the inclined groove connect with one of the inlet channel and the reflux channel, or can make the inclined groove blocked with both the inlet channel and the reflux channel.

[0007] The inclined groove has a certain length and is arranged along the peripheral wall of the rotating shaft to form a spiral groove.

[0008] As an improvement, the upper end of the piston is provided with a mounting cavity, the lower end of the rotating shaft is inserted into and mounted in the mounting cavity, an annular boss is provided on the outer peripheral wall of the lower end of the rotating shaft, a sealing ring is provided between the rotating shaft and the inner peripheral wall of the mounting cavity, and the mounting cavity is connected through an oil drain channel on the piston. The mounting cavity is connected with the oil drain channel, and the oil drain channel is connected with the low-pressure area, so that the mounting cavity below the rotating shaft is always at low pressure, so that the oil pressure can act on the annular boss with a very small cross-sectional area, exerting a force on the rotating shaft to move in the direction of the piston, so as to better ensure that the rotating shaft can move axially with the piston.

[0009] As a further improvement, a ball bearing is provided between the bottom surface of the rotating shaft and the inner bottom surface of the installation cavity. The provision of the ball bearing makes the rotating shaft rotate more easily. To ensure that the sealing ring is securely installed between the rotating shaft and the inner peripheral wall of the installation cavity, the sealing ring is pressed by a pressing ring.

[0010] Preferably, the rotating shaft is driven to rotate by a driving mechanism, and the output shaft of the driving mechanism is connected to the rotating shaft through a transmission joint. The transmission joint and the rotating shaft are connected by an axis groove structure, and the axis groove structure includes a vertically extending slide groove and a driving shaft that can slide up and down in the slide groove. The slide groove is provided at one of the transmission joint and the rotating shaft, and the driving shaft is provided at the other of the transmission joint and the rotating shaft.

[0011] More specifically, when the slide slot is provided in the transmission joint, the transmission joint is shaft-shaped and has an insertion cavity with an opening facing downward, the peripheral wall of the insertion cavity is provided with a slide slot, the driving shaft is provided at the upper end of the rotating shaft; the upper end of the transmission joint is provided with a first slot for the output shaft of the driving mechanism to be plugged in. The driving mechanism is preferably a motor, and the rotating shaft is driven by the motor, which is conducive to automatic control. The rotating shaft can also be driven to rotate in other ways.

[0012] Alternatively, the thrust mechanism is a spring acting on the lower end of the piston. When the inlet channel is connected to the chute, the force of the upper pressure chamber on the piston is greater than the force of the spring on the piston, and the piston moves downward; when the return channel is connected to the chute, the force of the upper pressure chamber on the piston is less than the force of the spring on the piston, and the piston moves upward; the upward or downward movement of the piston can block the inlet channel and the return channel from the chute. Using a spring to provide an upward thrust to the piston has the advantages of simple structure and low cost.

[0013] Preferably, the thrust mechanism is a lower pressure chamber located at the lower end of the piston, and the lower pressure chamber is connected to the oil inlet. The area of ​​the upper force-bearing surface of the piston acted on by the pressure oil in the upper pressure chamber is larger than the area of ​​the lower force-bearing surface of the piston acted on by the pressure oil in the lower pressure chamber. The thrust mechanism is conducive to the provision of oil pressure, and the oil inlet itself exists on the valve body, so the design is more reasonable. Using oil pressure as the upward thrust to the piston has the advantage of high precision control, and can still maintain high control accuracy even after long-term use. The pressure oil in the upper pressure chamber and the pressure oil in the lower pressure chamber can be provided by the same pressure oil circuit, and divided into two ways to connect to the upper pressure chamber and the lower pressure chamber from the outside of the piston respectively. It can also be provided by different pressure oil circuits. The key is that when the upper and lower pressure chambers are both passed through oil, the two can form a pressure difference, so that the piston can be controlled to move up or down by changing the pressure difference. For example, when the lower pressure chamber and the upper pressure chamber are supplied with oil by the same pressure oil circuit, the pressure in the upper pressure chamber and the lower pressure chamber is equal. Because the area of ​​the upper force-bearing surface and the lower force-bearing surface is different, it is easy to generate a pressure difference at both ends of the piston, thereby controlling the movement of the piston. Using oil pressure as the upward thrust for the piston has the advantage of high precision control. Even if it is used for a long time, it can still maintain a high control accuracy. In addition, the oil pressure is easy to produce a balance at both ends of the piston, effectively ensuring that the piston remains in a certain set position reflux channel. In the process of the piston moving up due to the pressure difference at both ends, when the pressure oil no longer enters the upper pressure chamber, and the upper pressure chamber is not connected to the reflux channel, the upper pressure chamber will neither enter nor leak oil. The piston has moved up to the limit position, and the hydraulic oil in the upper pressure chamber can no longer be compressed. Therefore, the forces at the upper and lower ends of the piston are balanced, so that the piston remains in the set position.

[0014] Specifically, based on the area difference of the above-mentioned force-bearing surfaces, when the inlet channel is connected to the inclined groove, the pressure oil enters the upper pressure chamber, the force of the upper pressure chamber acting on the piston is greater than the force of the lower pressure chamber acting on the piston, and the piston moves downward; when the return channel is connected to the inclined groove, the pressure oil is discharged from the upper pressure chamber, the oil pressure is reduced, the force of the upper pressure chamber acting on the piston is less than the force of the lower pressure chamber acting on the piston, and the piston moves upward; the upward or downward movement of the piston can block the inlet channel and the return channel from the inclined groove.

[0015] The function of the above-mentioned thrust mechanism is to apply an upward thrust to the lower end of the piston, so that the piston can move upward in the piston cavity. Therefore, the above-mentioned thrust mechanism may include a coil spring, a pneumatic spring, a torsion spring and other similar elastic mechanisms, and may also include a permanent magnet, an electromagnet, an oil cylinder, a gas cylinder and the like. As long as an upward thrust can be applied to the lower end of the piston, it can be used as the thrust mechanism described in the utility model.

[0016] Preferably, when the chute is blocked from both the inlet channel and the return channel, the inlet channel and the return channel are located on both sides of the chute. In this way, the rotating shaft can be rotated in one direction to connect the chute with the inlet channel, and rotated in the opposite direction to connect the chute with the return channel. This is more conducive to control, and the drive mechanism can be rotated within a smaller angle range to achieve axial movement of the piston. Digital control can be easily achieved through the circuit that controls the rotation of the drive mechanism. The drive mechanism integrated control circuit can control the rotating shaft through input signals.

[0017] Fluid flows in the inlet channel, the return channel, the upper pressure chamber, and the lower pressure chamber, and can be liquids such as air, water, and hydraulic oil, with hydraulic oil being the best.

[0018] Compared with the prior art, the advantages of the piston stroke control mechanism are:

[0019] 1. By additionally setting up a transition conversion shaft with an inlet channel and a return channel therein, there is no need to process various complicated channels in the piston. The transition conversion shaft is shorter than the piston and is a fixed part, which is conducive to designing and processing channels inside it, thereby greatly improving production efficiency.

[0020] 2. By driving the rotating shaft to rotate, the inclined groove is connected to either the inlet channel or the return channel, thereby changing the oil pressure in the upper pressure chamber; when the inlet channel is connected to the inclined groove, the oil pressure in the upper pressure chamber increases, thereby increasing the force of the pressure oil acting downward on the piston, and the force of the upper pressure chamber acting on the piston is greater than the force of the thrust mechanism acting on the piston, so the piston can move downward and drive the rotating shaft downward. Because it is an inclined groove, the oil port opening will gradually decrease along the axis line until it stops moving downward at 0; when the return channel is connected to the inclined groove, the oil pressure in the upper pressure chamber decreases, thereby reducing the force of the pressure oil acting downward on the piston. Under the action of the thrust mechanism, the piston can move upward and drive the rotating shaft upward. The oil port opening will gradually decrease along the axis line until it stops moving upward at 0. The larger the rotation angle, the longer the stroke of the axis. The rotation angle determines the stroke, and the rotating shaft moves axially with the piston. Because the connection is point contact, the concentricity requirements between the rotating shaft and the piston and the upper pressure chamber are greatly reduced. There will be no axial sliding friction between the rotating shaft and the piston, and the assembly is simpler. The product qualification rate can be greatly improved, and the plug-in stability is better, which greatly reduces the failure rate. The connection between the piston and the rotating shaft can be any connection as long as a rotatable and self-aligning connection can be achieved.

[0021] 3. This control mechanism only needs to control the rotation axis to rotate within 90 degrees or even a smaller angle, and the maximum stroke displacement of the piston can be controlled by the servo motor. The speed time can often be completed in a few milliseconds, with good dynamic response characteristics. In addition, the core components of this control mechanism are the rotation axis and the piston, which have a simple relationship with each other, so the cost is low and the structure is simple and reasonable. The thrust mechanism can make it easier to form a pressure difference between the upper and lower ends of the piston. After the upper pressure chamber is drained and depressurized, the piston can move up better, and when the upper pressure chamber is filled with oil and pressurized, the piston can move down better.

[0022] 4. To drive the rotation of the rotating shaft, only a small force is needed. For example, a servo motor can easily drive the piston to rotate. Even if a large-diameter piston is driven, the energy consumption required is very small, which is more energy-saving. The motor can easily drive the rotating shaft to rotate, and if a servo motor is used, the motor rotation angle can be accurately controlled. The motor control responds quickly. For the entire control stroke, the motor only needs to rotate 90 degrees or even less. The rotation angle can be accurately controlled through the encoder. The motor rotation angle can be converted into the position of the piston moving up and down through the rotating shaft, and the built-in rotary encoder can be used to read and feedback the current piston position, thereby controlling the piston stroke and improving the accuracy of the control mechanism. Of course, other mechanisms can also be used to drive the rotating shaft to rotate.

[0023] 5. When the piston moves to the set position, the inlet channel and the return channel are blocked from the chute, and the upper pressure chamber neither enters nor leaks oil, so that the forces at the upper and lower ends of the piston are balanced, and the piston can be kept in the set position without the need for continuous power supply, thus avoiding the traditional solenoid valve that requires the solenoid coil to be constantly powered to maintain the set position of the piston. Compared with the servo valve high-frequency response method to dynamically adjust the piston position (control pressure loss), it is more energy-efficient

[0024] 6. The intermittent forward or reverse rotation of the aforementioned rotating shaft is a decomposed action to fully demonstrate the axial movement process and principle of the piston, so that those skilled in the art can thoroughly understand the present utility model; of course, in actual application, based on the pre-designed program and given parameters, the rotation of the rotating shaft can be continuous, and the displacement of the piston is also continuous. For this reason, the displacement of the piston can be accurately controlled by controlling the rotation angle of the rotating shaft.

[0025] The second technical problem to be solved by the utility model is to provide a variable displacement pump with a simple and reasonable structure, good dynamic response characteristics, and the ability to accurately control the swing angle of the variable displacement head in response to the above-mentioned existing technical status.

[0026] The technical solution adopted by the utility model to solve the second technical problem is: a variable pump, including a variable head, characterized in that it also includes the aforementioned piston stroke control mechanism, the variable head is swingably connected to the piston, so that the axial movement of the piston drives the variable head to swing. The variable head is swingably connected to the piston through a ball head structure. The setting of the ball head structure can make the axial movement of the piston easier to drive the variable head to swing.

[0027] Compared with the prior art, the advantages of the variable pump are: the variable pump controls the swing angle of the variable head through the axial movement amplitude of the piston, and the aforementioned piston stroke control mechanism has good dynamic response characteristics, and the displacement of the piston can be accurately controlled by controlling the rotation angle of the rotating shaft. Therefore, the control of the swing of the variable pump also has good dynamic response characteristics, and the swing angle of the variable head can be accurately controlled. Of course, the aforementioned piston stroke control mechanism can be used in other fields or products, such as variable plunger pumps, variable gear pumps, variable vane pumps, hydraulic valves, hydraulic cylinders, and hydraulic transformers.

[0028] The third technical problem to be solved by the utility model is to provide a hydraulic reversing valve with a simple and reasonable structure, good dynamic response characteristics, and the ability to accurately control the movement of the piston in response to the above-mentioned existing technical status.

[0029] The technical solution adopted by the utility model to solve the third technical problem is: a hydraulic reversing valve, characterized in that it includes the aforementioned piston stroke control mechanism, and the piston is provided with a plurality of annular grooves. The opening and closing of the piston (traditionally called the valve core) and the oil circuit and the opening size are precisely controlled, while the existing technology can only control the opening and closing switching, but cannot control the opening size. The other structures of the reversing valve are consistent with the existing reversing valve structure and principle. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 The three-dimensional structure diagram of the variable displacement pump embodiment of the utility model is shown in FIG. Figure 1 ;

[0031] Figure 2 The three-dimensional structure diagram of the variable displacement pump embodiment of the utility model is shown in FIG. Figure 2 ;

[0032] Figure 3 It is a cross-sectional view of an embodiment of a variable displacement pump including a piston stroke control mechanism of the utility model (the chute is connected to the reflux channel);

[0033] Figure 4 for Figure 3 A magnified image of point A;

[0034] Figure 5 for Figure 3 BB section view;

[0035] Figure 6 for Figure 3 CC cross-section Figure 1 (The posture in which the inclined groove 51 of the rotating shaft 5 is connected to the inlet channel and the return channel T of the transition conversion shaft 8);

[0036] Figure 7 for Figure 3 CC cross-section Figure 2 (the chute 51 and the inlet channel P and the return channel T are all blocked);

[0037] Figure 8 for Figure 3 CC cross-section Figure 3 (state in which the inclined groove 51 of the rotating shaft 5 is connected to the inlet channel P of the transition conversion shaft 8);

[0038] Fig. 9 The three-dimensional structure diagram of the rotating shaft of the utility model is shown in FIG.

[0039] Fig.10 It is a three-dimensional structural schematic diagram of the piston of the utility model;

[0040] Fig.11 It is a three-dimensional structural schematic diagram of the transition conversion shaft of the utility model;

[0041] Fig.12 This is a three-dimensional exploded view of the piston stroke control mechanism of the utility model (the valve body is hidden);

[0042] Fig.13 It is a hydraulic reversing valve with a piston stroke control mechanism of the utility model;

[0043] Fig.14 It is an independent schematic diagram of the piston stroke control mechanism, which can be expanded to various application scenarios. DETAILED DESCRIPTION

[0044] The present invention will be described in further detail below in conjunction with the accompanying drawings.

[0045] like Figures 1 to 12 The figure shows a preferred embodiment of the variable displacement pump using a piston stroke control mechanism of the utility model.

[0046] A variable displacement pump comprises a variable displacement head and a piston stroke control mechanism.

[0047] The piston stroke control mechanism in this embodiment includes a valve body 1, a piston 3, and a rotating shaft 5. The piston 3 is columnar, and a piston cavity is provided in the valve body 1. The piston 3 is arranged in the piston cavity so that it can only move axially up and down and cannot rotate. For example, if a certain section of the cross section of the piston 3 is a non-circular structure, the cross section of a section of the piston cavity at the corresponding position is also a non-circular structure, so that the piston 3 can only move up and down. The piston chamber includes an upper pressure chamber 11 located at the upper end of the piston 3. A thrust mechanism is provided below the piston 3 to enable it to move upward. The rotating shaft 5 extends into the upper pressure chamber 11 and is inserted into the piston 3 and can rotate around its own axis. The rotating shaft 5 is driven to rotate by the driving mechanism 7, and the driving mechanism 7 is preferably a servo motor; the output shaft of the driving mechanism 7 is connected to the rotating shaft 5 through a transmission joint 9, the transmission joint 9 is shaft-shaped and has an insertion chamber 91 with the mouth end facing downward, the upper end of the transmission joint 9 is provided with a slot 911 for the output shaft of the driving mechanism 7 to be plugged in, and the peripheral wall of the insertion chamber 91 is provided with a symmetrically arranged slide groove 912, and the upper end of the rotating shaft 5 is provided with a driving shaft 6, which is arranged in the slide groove 912 and can be moved. The variable head 2 is swingably connected to the piston 3, so that the axial movement of the piston 3 drives the variable head 2 to swing. The variable head 2 is swingably connected to the piston 3 through a ball head structure. The other parts of the variable pump refer to the existing variable plunger pump structure.

[0048] The rotating shaft 5 can also move along the axial direction with the piston 3. The upper end of the piston 3 is provided with a mounting cavity 31. The lower end of the rotating shaft 5 is inserted into and mounted in the mounting cavity 31. A ball 4 is provided between the bottom surface of the rotating shaft 5 and the inner bottom surface of the mounting cavity 31. An annular boss 52 is provided on the outer peripheral wall of the lower end of the rotating shaft 5. A sealing ring 10 is provided between the rotating shaft 5 and the inner peripheral wall of the mounting cavity 31. The sealing ring 10 is pressed by a pressure ring 101. The mounting cavity 31 is connected with the oil leakage channel 3a on the piston 3. Since the mounting cavity 31 is connected with the oil leakage channel 3a, and the oil leakage channel 3a is connected with the low-pressure area, it is ensured that the mounting cavity 31 below the rotating shaft is always at low pressure. In this way, the oil pressure can act on the annular boss 52 with a very small cross-sectional area, and exert a force on the rotating shaft 5 to move toward the piston 3, so as to better ensure that the rotating shaft 5 can move axially with the piston 3.

[0049] A transition conversion shaft 8 is fixed in the upper pressure chamber 11. The transition conversion shaft 8 is fixed in the upper pressure chamber 11 through a flange. An inlet channel P and a return channel T are provided on the transition conversion shaft 8. The rotating shaft 5 is passed through the transition conversion shaft 8. An inclined groove 51 communicating with the upper pressure chamber 11 is provided on the outer peripheral wall of the rotating shaft 5. The inclined groove 51 refers to an inclined groove structure having a certain length and arranged obliquely along the peripheral wall of the rotating shaft 5, so as to have a certain spiral shape. It can be one inclined groove 51. The best is that the inclined groove 51 has two symmetrical arrangements to form a similar double helix structure. The rotation of the rotating shaft 5 can make the inclined groove 51 communicate with one of the inlet channel P and the return channel T, so that the piston moves up or down. When the inlet channel P and the return channel T are blocked by the inclined groove 51, the inlet channel P and the return channel T are respectively located on both sides of the inclined groove 51. Then the piston 3 stops moving.

[0050] The thrust mechanism in this embodiment is a lower pressure chamber 12 located at the lower end of the piston 3, and the lower pressure chamber 12 is connected to the oil inlet 14 of the valve body 1; the rotation of the rotating shaft 5 can make the inclined groove 51 connected to either the inflow channel P or the return channel T, or make the inclined groove 3 blocked from both the inflow channel P and the return channel T, and the area of ​​the upper force-bearing surface 3a of the piston 3 acted by the pressure oil in the upper pressure chamber 11 is larger than the area of ​​the lower force-bearing surface 3b of the piston 3 acted by the pressure oil in the lower pressure chamber 12. When the inflow channel P is connected to the inclined groove 51, the force of the upper pressure chamber 11 on the piston 3 is greater than the force of the lower pressure chamber 12 on the piston 3, and the piston 3 moves downward; when the return channel T is connected to the inclined groove 51, the force of the upper pressure chamber 11 on the piston 3 is less than the force of the lower pressure chamber 12 on the piston 3, and the piston 3 moves upward; the upward or downward movement of the piston 3 can block both the inflow channel P and the return channel T from the inclined groove 51. Therefore, oil neither enters nor is discharged from the upper pressure chamber 11, and the upper and lower pressures of the piston are balanced.

[0051] Of course, the thrust mechanism can also be a spring acting on the lower end of the piston 3, and as a preferred spring, it can be placed in the lower pressure chamber 12. When the inlet channel P is connected to the chute 51, the force of the pressure oil in the upper pressure chamber 11 acting on the piston 3 is greater than the force of the spring acting on the piston 3, and the piston 3 moves downward; when the return channel T is connected to the chute 51, the force of the upper pressure chamber 11 acting on the piston 3 is less than the force of the spring acting on the piston 3, and the piston 3 moves upward; the upward or downward movement of the piston 3 can block the inlet channel P and the return channel T from the chute 51. This embodiment is not shown in the drawings.

[0052] The working principle and process of this piston stroke control mechanism are as follows:

[0053] In this embodiment and other embodiments, the fluid flowing in the valve body is hydraulic oil. When the driving mechanism 7 drives the rotating shaft 5 to rotate in the positive direction by an angle, such as Figures 3 to 6As shown, the inclined groove 51 on the rotating shaft 7 is connected to the reflux channel T and blocked with the inflow channel P. The pressure oil in the upper pressure chamber 11 is discharged through the reflux channel T on the transition conversion shaft 8. The upper pressure chamber 11 is depressurized, and the pressure oil at the oil inlet 14 still flows to the lower pressure chamber 12. Therefore, the piston 3 moves upward under the action of the oil pressure, and the rotating shaft 5 also moves upward. The greater the angle of rotation of the rotating shaft 5 in this direction, the greater the distance the piston 3 moves upward. When the driving mechanism 7 stops working, the rotating shaft 5 moves up to the inclined groove 3 and is blocked with the inflow channel P and the reflux channel T on the transition conversion shaft 8, as shown in FIG. Figure 7 As shown, the upper pressure chamber 11 is no longer depressurized and no pressurized oil continues to enter. The force of the upper pressure chamber 11 on the piston 3 is just balanced with the force of the lower pressure chamber 12 on the piston 3, and the piston 3 remains in this position.

[0054] On the contrary, when the driving mechanism 7 drives the rotating shaft 5 to rotate in the opposite direction by an angle, Figure 8 As shown, the inclined groove 51 on the rotating shaft 7 is connected with the inlet channel P, and the pressure oil of the oil inlet 14 flows to the lower pressure chamber 12, and at the same time, flows to the upper pressure chamber 11 after passing through the inclined groove 51, so that the pressure in the upper pressure chamber 11 and the lower pressure chamber 12 reaches the same, but the area of ​​the upper force-bearing surface 3a of the piston 3 acted by the pressure oil in the upper pressure chamber 11 is larger than the area of ​​the lower force-bearing surface 3b of the piston 3 acted by the pressure oil in the lower pressure chamber 12. Under the same pressure, a pressure difference is formed, that is, the downward pressure on the piston 3 is greater than the upward pressure, and the piston 3 moves downward axially. At the same time, the oil pressure in the upper pressure chamber 11 also acts on the annular boss 52 of the rotating shaft 5, so that the rotating shaft 5 also moves downward with the piston 3. The greater the angle of rotation of the rotating shaft 5 in this direction, the greater the distance the piston 3 moves downward. When the driving mechanism 7 stops working, the piston 3 moves down to the inclined groove 51 and the inlet channel P and the return channel T on the transition conversion shaft 8 are blocked, and the upper pressure chamber 11 will neither have pressure oil continuing to enter nor be depressurized. The force of the upper pressure chamber 11 acting on the piston 3 through the pressure oil and the force of the lower pressure chamber 12 acting on the piston 3 through the pressure oil are just balanced, and the piston 3 remains in this position.

[0055] The variable pump changes the swing angle of the variable head 2, which is driven by the axial movement of the piston 3, and finally realizes the flow rate of oil pumped out per unit time (i.e., the displacement of the pump). This is a conventional design of a variable pump.

[0056] The above is the intermittent forward or reverse rotation of the rotating shaft 5, which is a decomposed action to fully demonstrate the up and down movement process and principle of the piston 3, so that those skilled in the art can thoroughly understand the present invention; of course, in actual application, based on the pre-designed program and given parameters, the rotation of the rotating shaft 5 can be continuous, and the displacement of the piston 3 is also continuous. For this reason, the displacement of the piston 3 can be accurately controlled by the angle of rotation of the rotating shaft 5 by the driving mechanism 7.

[0057] like Fig.13 The figure shows a preferred embodiment of the hydraulic reversing valve using a piston stroke control mechanism of the utility model.

[0058] A hydraulic reversing valve adopts a piston stroke control mechanism, including a valve body 1, a piston 3, a rotating shaft 5, and a transition conversion shaft 8. The valve body 1 is provided with an oil inlet 1a, a reflux channel 1b, and multiple oil outlets 1c. Its piston stroke control mechanism is the same as above, and the piston 3 is provided with multiple annular grooves 32.

[0059] The reversing principle of the reversing valve is similar to that of a conventional reversing valve, and the moving principle of the piston 3 is the same as that of the variable displacement pump embodiment.

[0060] Compared with the previous electromagnetic reversing valve, the previous electromagnetic reversing valve only has a switch and cannot directly control the displacement. The displacement must be controlled through high-frequency switching, but this will lose a lot of control pressure, which is very wasteful. The hydraulic reversing valve using the piston stroke control mechanism can be directly converted into displacement control, with very little energy loss and more energy saving.

[0061] The above two embodiments are embodiments of the piston stroke control mechanism under specific application scenarios. However, the core lies in the piston stroke control mechanism, which has been reflected in the above two embodiments, but it can exist independently and can be expanded to other application scenarios. Fig.14 shown.

[0062] It should be noted that in the description of this embodiment, the terms "front, back", "left, right", "inside, outside", "upper, lower" and the like indicating directions or positional relationships are all based on the directions 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 direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the present invention. The terms "install", "connect", 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 direct connection, or an indirect connection through an intermediate medium, or it can be a connection between the two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances.

Claims

1. A piston stroke control mechanism, comprising a valve body (1), a piston (3), and a rotating shaft (5), wherein a piston chamber is provided in the valve body (1), the piston (3) is arranged in the piston chamber and can move axially, the piston chamber comprises an upper pressure chamber (11) located at the upper end of the piston (3), a thrust mechanism is provided below the piston (3) to enable the piston (3) to move upward, the rotating shaft (5) extends into the upper pressure chamber (11) and can rotate around its own axis; the characteristics are: The rotating shaft (5) can also move up and down along the axial direction with the piston (3); a transition conversion shaft (8) is fixed above the upper pressure chamber (11); the transition conversion shaft (8) is provided with an inlet channel (P) and a return channel (T); the rotating shaft (5) passes through the transition conversion shaft (8); an inclined groove (51) communicating with the upper pressure chamber (11) is provided on the outer peripheral wall of the rotating shaft (5); the rotation of the rotating shaft (5) can make the inclined groove (51) communicate with one of the inlet channel (P) and the return channel (T), or can make the inclined groove (51) blocked from both the inlet channel (P) and the return channel (T).

2. The piston stroke control mechanism according to claim 1, characterized in that: The upper end of the piston (3) is provided with a mounting cavity (31), the lower end of the rotating shaft (5) is mounted in the mounting cavity (31), an annular boss (52) is provided on the outer peripheral wall of the lower end of the rotating shaft (5), a sealing ring (10) is provided between the rotating shaft (5) and the inner peripheral wall of the mounting cavity (31), and the mounting cavity (31) is connected through an oil drain channel (3c) on the piston (3).

3. The piston stroke control mechanism according to claim 2, characterized in that: The sealing ring (10) is pressed by a pressure ring (101); and a ball (4) is provided between the bottom surface of the rotating shaft (5) and the bottom surface of the mounting cavity (31).

4. The piston stroke control mechanism according to claim 1, characterized in that: The rotating shaft (5) is driven to rotate by a driving mechanism (7); the output shaft of the driving mechanism (7) is connected to the rotating shaft (5) via a transmission joint (9); the transmission joint (9) and the rotating shaft (5) are connected by an axis groove structure; the axis groove structure comprises a vertically extending slide groove (912) and a driving shaft (6) that can slide up and down in the slide groove (912); the slide groove (912) is provided on one of the transmission joint (9) and the rotating shaft; and the driving shaft (6) is provided on the other of the transmission joint (9) and the rotating shaft.

5. The piston stroke control mechanism according to claim 4, characterized in that: When the slide groove (912) is arranged on the transmission joint (9), the transmission joint (9) is shaft-shaped and has an insertion cavity (91) with an opening facing downward, the slide groove (912) is arranged on the peripheral wall of the insertion cavity (91), and the driving shaft (6) is arranged on the upper end of the rotating shaft (5); the upper end of the transmission joint (9) is provided with a slot (911) for the output shaft of the driving mechanism (7) to be plugged in.

6. The piston stroke control mechanism according to claim 1, characterized in that: The thrust mechanism is a spring acting on the lower end of the piston (3). When the inlet channel (P) is connected to the inclined groove (51), the force of the upper pressure chamber (11) acting on the piston (3) is greater than the force of the spring acting on the piston (3), and the piston (3) moves downward; when the return channel (T) is connected to the inclined groove (51), the force of the upper pressure chamber (11) acting on the piston (3) is less than the force of the spring acting on the piston (3), and the piston (3) moves upward. The upward or downward movement of the piston (3) can block the inlet channel (P) and the return channel (T) from the inclined groove (51).

7. The piston stroke control mechanism according to claim 1, characterized in that: The thrust mechanism is a lower pressure chamber (12) located at the lower end of the piston (3), and the lower pressure chamber (12) is connected to the oil inlet (14) of the valve body (1); the area of ​​the upper force-bearing surface (3a) of the piston (3) in the upper pressure chamber (11) is greater than the area of ​​the lower force-bearing surface (3b) of the piston (3) in the lower pressure chamber (12).

8. The piston stroke control mechanism according to claim 7, characterized in that: When the inlet channel (P) is connected to the inclined groove (51), the force of the upper pressure chamber (11) acting on the piston (3) is greater than the force of the lower pressure chamber (12) acting on the piston (3), and the piston (3) moves downward; when the return channel (T) is connected to the inclined groove (51), the force of the upper pressure chamber (11) acting on the piston (3) is less than the force of the lower pressure chamber (12) acting on the piston (3), and the piston (3) moves upward; The upward or downward movement of the piston (3) can block the inlet channel (P) and the return channel (T) from the inclined groove (51).

9. A variable displacement pump, comprising a variable displacement head (2), characterized in that: It also comprises a piston stroke control mechanism as claimed in any one of claims 1 to 8, wherein the variable head (2) is swingably connected to the piston (3), so that the axial movement of the piston (3) drives the variable head (2) to swing.

10. A hydraulic reversing valve, characterized in that: It comprises a piston stroke control mechanism as claimed in any one of claims 1 to 8, wherein a plurality of annular grooves (32) are formed on the piston (3).

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