System and Method for Controlling Valve Needle Stroke

Abstract

The present invention provides a system and method for controlling the stroke of a valve needle, belonging to the technical field of injection molding processing. It includes a hydraulic power mechanism, and the hydraulic power mechanism is connected to at least one oil cylinder through a reversing valve. The oil cylinder includes a cylinder shell, and an oil cylinder cavity is arranged in the cylinder shell. The oil cylinder cavity is divided into an upper cavity and a lower cavity by an L-shaped oil cylinder piston, and the outer end of the oil cylinder piston penetrates through the cylinder shell. A valve needle fixing structure capable of installing a valve needle is arranged at the outer end of the oil cylinder piston. A first oil port of the upper cavity and a second oil port of the lower cavity are respectively connected to the reversing valve through a first pipeline and a second pipeline. A stroke adjusting mechanism for storing hydraulic oil and capable of assisting in controlling the working stroke of the oil cylinder piston is arranged on the first pipeline or the second pipeline. The present invention precisely adjusts the stroke of the valve needle by setting a stroke adjusting mechanism for storing hydraulic oil and capable of assisting in controlling the working stroke of the oil cylinder piston.

Description

Technical Field

[0001] The present invention belongs to the technical field of injection molding processing, and relates to a system and method for controlling the stroke of a valve pin. Background Art

[0002] In an injection mold, molten material is injected into the mold through one or more injection nozzles, and the opening and closing of the injection nozzles are controlled by an actuator. For complex parts produced by a multi-injection method, the position control of the valve pin for opening and closing the nozzle is the basis for obtaining high-quality finish. Because adjusting or changing the stroke of the valve pin determines the remaining space between the nozzle and the valve pin in the hot runner, and thus determines the flow rate of the molten material and the speed of entering the mold. Currently, in order to obtain high-value molded products, a numerical control oil cylinder is used to control the valve pin. However, the numerical control oil cylinder has a complex structure, high manufacturing cost and high operation difficulty. The cost of using a hydraulic cylinder is lower, but the prior art cannot accurately adjust the stroke of the valve pin. For example, Chinese Utility Model Patent [CN201020166097.0] discloses a hydraulic cylinder with adjustable valve pin stroke, which at least includes a cylinder body having an inner cavity, a cylinder core installed in the inner cavity of the cylinder body, and a valve pin installed at the outer end of the cylinder core. An adjusting block is also sleeved between the side wall of the cylinder body and the cylinder core. A plurality of limit grooves are provided on the periphery of the adjusting block, and limit holes matching the plurality of limit grooves are provided on the side wall of the cylinder body; the adjusting block and the steel core are connected by screw thread. The valve pin adjustment is manual adjustment and has a limited range, and the stroke of the valve pin cannot be accurately adjusted. Summary of the Invention

[0003] The object of the present invention is to provide a system for controlling the stroke of a valve pin in view of the above problems.

[0004] Another object of the present invention is to provide a method for controlling the stroke of a valve pin.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A system for controlling the stroke of a valve pin includes a hydraulic power mechanism. The hydraulic power mechanism is connected to at least one oil cylinder through a reversing valve. The oil cylinder includes a cylinder shell, and an oil cylinder cavity is provided in the cylinder shell. The oil cylinder cavity is divided into an upper cavity and a lower cavity by an L-shaped oil cylinder piston, and the outer end of the oil cylinder piston penetrates through the cylinder shell. A valve pin fixing structure capable of installing a valve pin is provided at the outer end of the oil cylinder piston. The first oil passage port of the upper cavity and the second oil passage port of the lower cavity are respectively connected to the reversing valve through a first pipeline and a second pipeline. A stroke adjusting mechanism for storing hydraulic oil and capable of assisting in controlling the working stroke of the oil cylinder piston is provided on the first pipeline or the second pipeline.

[0007] In the above system for controlling the valve needle stroke, the stroke adjusting mechanism includes an auxiliary tank. An inner cavity is provided in the auxiliary tank. An auxiliary piston capable of dividing the inner cavity into a left chamber and a right chamber is provided in the inner cavity. The outer end of the piston rod of the auxiliary piston penetrates through the auxiliary tank housing. An inner cavity volume adjusting assembly capable of adjusting the volume of the inner cavity is provided between the auxiliary piston and the auxiliary tank. Left and right liquid inlet and outlet ports respectively communicating with the left chamber and the right chamber are further provided on the auxiliary tank.

[0008] In the above system for controlling the valve needle stroke, the inner cavity volume adjusting assembly includes a moving sealing plate capable of axially moving in the left chamber and / or the right chamber. The outer wall of the moving sealing plate is slidably and sealingly connected to the inner wall of the inner cavity. A sealing plate adjusting assembly capable of adjusting the axial position of the moving sealing plate is provided between the moving sealing plate and the auxiliary tank.

[0009] In the above system for controlling the valve needle stroke, the moving sealing plate adjusting assembly includes an adjusting knob. The adjusting knob penetrates through the auxiliary tank and is threadedly connected thereto.

[0010] A servo boosting mechanism is connected to the adjusting knob.

[0011] The moving sealing plate and the adjusting knob are sleeved on the piston rod. An oil seal is provided between the adjusting knob and the piston rod.

[0012] The moving sealing plate adjusting assembly includes an electric boosting cylinder fixed on the outer wall of the auxiliary tank. The output end of the electric boosting cylinder penetrates through the auxiliary tank and is connected to the moving sealing plate.

[0013] The inner end of the piston rod is connected to the auxiliary piston and integrally formed.

[0014] The left liquid inlet and outlet port is provided at one end of the auxiliary piston in the left chamber and is connected to a first joint on the outer end of the piston rod through a first liquid guiding channel. The right liquid inlet and outlet port is provided at one end of the auxiliary piston in the right chamber and is connected to a second joint on the outer end of the piston rod through a second liquid guiding channel.

[0015] In the above system for controlling the valve needle stroke, a stroke limiting assembly capable of limiting the linear movement stroke of the auxiliary piston is provided between the auxiliary piston and the auxiliary tank.

[0016] The stroke limiting assembly includes a mechanical support provided between the auxiliary piston and the auxiliary tank and capable of limiting the linear movement of the auxiliary piston.

[0017] In the above system for controlling the valve needle stroke, flow regulating valves are provided between the reversing valve and both the stroke adjusting mechanism and the oil cylinder. The flow regulating valves are provided on the corresponding first pipeline and second pipeline.

[0018] In the above system for controlling the stroke of the valve needle, the oil cylinder is fixed on the hot runner mold through a connecting seat. The hot runner mold is provided with an inverted fluid channel. The valve needle is arranged in the fluid channel through a valve needle mounting hole. A nozzle is provided at the lower end of the fluid channel, and a limiting flow-blocking structure is arranged between the nozzle and the valve needle.

[0019] The limiting flow-blocking structure includes a nozzle gate arranged in the nozzle. The nozzle gate matches the lower end of the valve needle, and the nozzle gate is conical or inverted trapezoidal.

[0020] In the above system for controlling the stroke of the valve needle, three oil cylinders are connected in parallel to the reversing valve.

[0021] A method for controlling the stroke of a valve needle is as follows:

[0022] S1. One end of the valve needle is installed on the valve needle fixing structure at the outer end of the oil cylinder piston;

[0023] S2. The hydraulic power mechanism supplies or extracts liquid to the upper cavity and the lower cavity of the oil cylinder through the first pipeline and the second pipeline;

[0024] S3. Adjust the total liquid supply volume of the upper cavity or the lower cavity through the stroke adjustment mechanism.

[0025] In the above method for controlling the stroke of the valve needle, in step S3, the inner cavity volume of the auxiliary tank is adjusted through the inner cavity volume adjustment component, so as to adjust the total liquid supply volume of the upper cavity or the lower cavity.

[0026] Compared with the existing technology, the advantages of the present invention are as follows:

[0027] 1. The system for controlling the stroke of the valve needle provided by the present invention accurately adjusts the stroke of the valve needle by setting a stroke adjustment mechanism for storing hydraulic oil and capable of assisting in controlling the working stroke of the oil cylinder piston. There is no need to transform the structure of the oil cylinder, the structure is simple, and the adjustment is accurate.

[0028] 2. The system for controlling the stroke of the valve needle provided by the present invention flexibly and accurately controls the stroke of the valve needle system by setting a movable sealing plate in the auxiliary tank, and at the same time, the stroke range of the valve needle can be controlled according to actual production needs, and the applicable scenarios are wide.

[0029] 3. The method for controlling the stroke of the valve needle provided by the present invention can accurately control the stroke of the valve needle in the oil cylinder by adjusting the total liquid supply volume of the upper cavity or the lower cavity of the oil cylinder; it can also adjust the total liquid supply volume of the upper cavity or the lower cavity by adjusting the inner cavity volume of the auxiliary tank through the inner cavity volume adjustment component, and further accurately control the stroke of the valve needle in the oil cylinder.

[0030] Other advantages, objects, and features of the present invention will be partially reflected by the following description and partially understood by those skilled in the art through the research and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is a schematic diagram of a system according to an embodiment provided by the present invention;

[0032] Figure 2 is a schematic diagram of a system according to another embodiment;

[0033] Figure 3 is a schematic diagram of a system according to another embodiment.

[0034] Figure 4 is a schematic diagram of an embodiment of a partial structure of the present invention.

[0035] Figure 5 is a schematic diagram of another embodiment of a partial structure of the present invention.

[0036] In the figure, hydraulic power mechanism 5, through reversing valve 40, oil cylinder 10, cylinder housing 16, oil cylinder cavity 18, oil cylinder piston 14, upper cavity 18a, lower cavity 18b, valve needle 12, valve needle fixing structure 15, first oil passage 19a, second oil passage 19b, first pipeline 20, second pipeline 22, stroke adjusting mechanism 6, auxiliary tank 60, inner cavity 66, left chamber 66a, right chamber 66b, auxiliary piston 64, piston rod 65, inner cavity volume adjusting component 7, left liquid inlet and outlet 60a, right liquid inlet and outlet 60b, moving sealing plate 70, sealing plate adjusting component 72, adjusting knob 74, electric assist cylinder 76, first liquid guiding channel 61a, first joint 65a, second liquid guiding channel 61b, second joint 65b, stroke limiting component 68, flow regulating valve 30, flow regulating valve 32, connecting seat 11, hot runner mold 90, fluid channel 92, valve needle mounting hole 94, nozzle 13, limiting flow blocking structure 8, nozzle gate 80, oil cylinder 10a, oil cylinder 10b, oil cylinder 10c, valve needle 12a, valve needle 12b, valve needle 12c. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0037] Embodiment 1

[0038] This embodiment provides a system for controlling the stroke of a valve needle, including a hydraulic power mechanism 5. The hydraulic power mechanism 5 is connected to at least one oil cylinder 10 through a reversing valve 40. The oil cylinder 10 includes a cylinder housing 16, and an oil cylinder cavity 18 is provided inside the cylinder housing 16. The oil cylinder cavity 18 is divided into an upper cavity 18a and a lower cavity 18b by an oil cylinder piston 14 in a T shape, and the outer end of the oil cylinder piston 14 penetrates through the cylinder housing 16. A valve needle fixing structure 15 capable of installing a valve needle 12 is provided at the outer end of the oil cylinder piston 14. The first oil passage 19a of the upper cavity 18a and the second oil passage 19b of the lower cavity 18b are respectively connected to the reversing valve 40 through a first pipeline 20 and a second pipeline 22. A stroke adjusting mechanism 6 for storing hydraulic oil and capable of assisting in controlling the working stroke of the oil cylinder piston 14 is provided on the first pipeline 20 or the second pipeline 22.

[0039] The working principle of the present invention is as follows: The oil cylinder piston 14 can be replaced / moved in the oil cylinder cavity 18 under the action of the pressurized fluid on the oil cylinder piston 14, and is connected to the valve needle 12 of the injection nozzle for the molten material used in injection molding. A stroke adjusting mechanism 6 for storing hydraulic oil and capable of assisting in controlling the working stroke of the oil cylinder piston 14 is provided on the first pipeline 20 or the second pipeline 22, which is used to forcibly transfer a predetermined amount of fluid in the oil cylinder cavity 18, move the valve needle 12 away from the closed position where no molten material passes, towards the open position where molten material passes, or move the valve needle 12 away from the open position where molten material passes to a closed position, and then no molten material flows in the fluid passage 92, extract the fluid from the oil cylinder cavity 18 and discharge it or inject fluid into the oil cylinder cavity 18. The valve needle 12 may or may not be part of the oil cylinder. The stroke adjusting mechanism 6 can adjust the total stroke of the oil cylinder 10 and the maximum stroke of the oil cylinder piston 14, corresponding to the opening and stroke limit of the valve needle 12. The reversing valve 40 can be a 2-position 4-way solenoid valve and can perform phase conversion. In each complete cycle, its function is to change the flow direction of the fluid in the circuit, and the flow direction of the fluid determines the opening or closing movement direction of the valve needle 12.

[0040] By the action of the pump, fluid is injected into the upper cavity 18a. Starting from the first pipeline 20, the valve needle 12 can be moved from the open position to the closed position, or to the end limit position of the closing stroke ( Figure 1 downward in

[0041] this). In this stage, the total amount of fluid Q1 injected into the upper cavity 18a from the first pipeline 20 can be determined.

[0042] Combined withFigure 1 As shown, the stroke adjustment mechanism 6 includes an auxiliary tank 60. An inner cavity 66 is provided in the auxiliary tank 60. An auxiliary piston 64 capable of dividing the inner cavity 66 into a left chamber 66a and a right chamber 66b is provided in the inner cavity 66. The outer end of the piston rod 65 of the auxiliary piston 64 penetrates the housing of the auxiliary tank 60. An inner cavity volume adjustment assembly 7 capable of adjusting the volume of the inner cavity 66 is provided between the auxiliary piston 64 and the auxiliary tank 60. A left liquid inlet / outlet 60a and a right liquid inlet / outlet 60b respectively communicating with the left chamber 66a and the right chamber 66b are further provided on the auxiliary tank 60.

[0043] Those skilled in the art should understand that the total amount of fluid Q1 injected into the upper cavity 18a from the first pipe 20 is consistent with the change in the total amount of fluid stored in the left chamber 66a. When the maximum volume reached when the upper cavity 18a is close to the end - stroke limit automatically determines the end - stroke limit of the piston, that is, when the auxiliary piston 64 moves towards the left chamber 66a, the end - stroke limit of the piston can be defined.

[0044] Under the action of the hydraulic power mechanism 5, fluid is injected into the lower cavity 18b. Starting from the second pipe 22, the valve needle 12 can move from the closed position to the open position, or move to the extreme end of the opening stroke ( Figure 1 upward in it). The fluid from the second pipe 22 pushes the oil cylinder piston 14 towards the upper cavity 18a. In turn, the oil cylinder piston 14 pushes the fluid from the upper cavity 18a into the left chamber 66a, causing the auxiliary piston 64 to move in the opposite direction.

[0045] At this stage, the liquid from the upper cavity 18a to the left chamber 66a is either alternating or in reverse. The quantity Q2 is determined by the average value of the stroke limit when the auxiliary piston 64 moves towards the right chamber 66b, and the stroke limit can be defined. Q1 = Q2, where the reverse stroke of the auxiliary piston 64 determines how much the displaced liquid volume of Q2 is.

[0046] The auxiliary tank 60 is configured to be able to change its own volume to Vmax and / or Vmin. The auxiliary tank 60 has the ability to adjust the fluid capacity. The liquid volume of the auxiliary tank 60 can be adjusted in various ways. For example, the auxiliary tank 60 includes an inner cavity 66 of a closed cavity adapted to hold the predetermined fluid volume; wherein the inner cavity 66 can reach a minimum volume Vmin and / or a maximum volume Vmax. The auxiliary tank 60 includes a deformable housing that defines the inner cavity 66; by using the inner cavity volume adjustment assembly 7, the inner cavity 66 can be made to reach the minimum volume Vmin and / or the maximum volume Vmax. The auxiliary tank 60 includes an auxiliary piston 64 that can move within the inner cavity 66 under the pressure of the fluid. The inner cavity 66 is divided by the auxiliary piston 64 into a left chamber 66a connected to the oil cylinder cavity 18 and a right chamber 66b. The right chamber 66b is fluidly connected to the hydraulic power mechanism 5 for forced transfer. The left chamber 66a and the right chamber 66b are on opposite sides of the auxiliary piston 64. The stroke of the auxiliary piston 64 is adjustable to determine the maximum and / or minimum volume of the left chamber 66a.

[0047] As shown in combination with Figure 4 The inner cavity volume adjustment assembly 7 includes a moving seal plate 70 disposed in the left chamber 66a and / or the right chamber 66b and capable of axially moving. The outer wall of the moving seal plate 70 is slidably and sealingly connected to the inner wall of the inner cavity 66. A seal plate adjustment assembly 72 capable of adjusting the axial position of the moving seal plate 70 is provided between the moving seal plate 70 and the auxiliary tank 60.

[0048] The moving seal plate 70 can be rigid or elastic; an expandable or contractible shell wall, for example, by changing the temperature of the shell wall or by elastic stretching of the shell wall. Or a method of filling the inner cavity 66 with a filling material and changing the total amount of the filling material in the closed cavity is used to achieve the same purpose. That is, the moving seal plate 70 determines the minimum volume Vmin and the maximum volume Vmax of the inner cavity 66.

[0049] As shown in combination with Figure 4 The moving seal plate adjustment assembly 72 includes an adjustment knob 74 that passes through the auxiliary tank 60 and is threadedly connected thereto.

[0050] A servo assist mechanism is connected to the adjustment knob 74.

[0051] The servo assist mechanism can be a mechanical, electrical, and / or electronic device for adjusting and controlling the piston stroke, such as a linear encoder, a rotary encoder, a laser or infrared reading system, a mechanical screw stop, a screw / nut system, an optical fiber, etc.

[0052] As shown in combination with Figure 1 A stroke limit assembly 68 capable of limiting the linear movement stroke of the auxiliary piston 64 is provided between the auxiliary piston 64 and the auxiliary tank 60.

[0053] The reverse stroke of the auxiliary piston 64 is adjusted by a manual or servo-assisted system 68 to determine the volume or flow rate of the fluid to be moved, introducing and / or extracting fluid from the 18a chamber to determine the required stroke, such as the opening stroke of the valve needle; for example, a stroke of 10 to 40 mm, such as 25 mm.

[0054] According to the manual or servo-assisted system 68, Q1 and Q2 can be changed. The geometry of the system ensures that the changes in the fluids Q1, Q2 are translated into corresponding displacements of the piston. The values of Q1 and Q2 determine the constraints for the movement of the cylinder piston 14 within the cylinder chamber 18 (limiting the movement distance of the cylinder piston 14), determining the magnitude of the stroke and / or the limit at the end of the stroke.

[0055] To compensate for any losses between the branches of the fluid circuit, the maximum volume of the fluid in the left chamber 66a is always greater than the maximum volume of the upper chamber 18a, so that there is the necessary fluid reserve to compensate for any losses between the branches of the fluid circuit. For the reverse movement of the valve needle, the first pipe 20 can be connected to the oil port 19a, and the pipe 22 can be connected to the oil port 19b.

[0056] The auxiliary tank 60 is equipped with a manual or servo-assisted 68 to adjust the inner cavity 66 of the auxiliary piston 64, so that the left chamber 66a can be adjusted to the maximum or minimum volume, and similarly for the right chamber 66b.

[0057] Furthermore, the stroke limiting assembly 68 includes a mechanical support provided between the auxiliary piston 64 and the auxiliary tank 60 that can limit the linear movement of the auxiliary piston 64.

[0058] The position of the auxiliary piston 64 can be detected by a linear encoder, a Hall sensor, a mechanical system based on a gear / nut screw device, etc.

[0059] Furthermore, flow control valves 30 and 32 are provided between the reversing valve 40 and the stroke adjusting mechanism 6 and the oil cylinder 10 respectively, and are respectively arranged on the corresponding first pipe 20 and second pipe 22.

[0060] In addition to smooth movement, the flow control valves 30 and 32 can also set different movement speeds of the cylinder piston 14.

[0061] The first conduit 20 allows fluid to pass through the oil inlet 19a and be transmitted from the cavity 18a to the cavity 66a and vice versa; the second conduit 22 allows fluid to pass through the oil inlet 19b and be transmitted from the cavity 18b to the cavity 66b and vice versa. Through the first conduit 20, fluid is injected into the upper cavity 18a on one side of the oil cylinder piston 14, while through the second conduit 22, fluid is injected into the lower cavity 18b on the other side of the oil cylinder piston 14. Similarly, through the first conduit 20, fluid is injected into the auxiliary piston 64 on one side of the auxiliary piston 64, while through the conduit 24, fluid is injected into the chamber 66b on one side of the piston 64. By injecting fluid from the second conduit 22 into the right chamber 66b, the auxiliary piston 64 is pushed onto the left chamber 66a. It is preferable to initially charge a certain amount of fluid into the upper cavity 18a and the left chamber 66a, or to compensate during operation, so as to compensate for the liquid leakage during the operation of the circuit.

[0062] Without changing the effects and advantages of the present invention, the displacement / movement direction of the fluid from the auxiliary tank 60 to the oil cylinder cavity 18 can be reversed, such as by interchanging the oil ports 19 and 19b.

[0063] In addition, the volume change of the inner cavity 66, or the transmission of fluid in the right chamber 66b can be achieved by driving the fluid with an air or gas drive system. Air or gas (compressible fluid) can also be used in the upper cavity 18a and the lower cavity 18b to achieve the change. This includes the addition or modification of some elements of the circuit, and the working principle remains unchanged.

[0064] Furthermore, the oil cylinder 10 is fixed on the hot runner mold 90 through the connecting seat 11. The hot runner mold 90 is provided with a fluid channel 92 in an inverted L shape. The valve pin 12 is arranged in the fluid channel 92 through the valve pin mounting hole 94. A nozzle 13 is provided at the lower end of the fluid channel 96, and a limiting flow-blocking structure 8 is arranged between the nozzle 13 and the valve pin 12.

[0065] The system for controlling the stroke of the valve pin may further include a mechanical system, such as spring operation, to ensure the movement of the oil cylinder 10 driving the valve pin 12 in one direction.

[0066] Those skilled in the art should understand that the limiting flow-blocking structure 8 includes a nozzle gate 80 arranged in the nozzle 13. The nozzle gate 80 matches the lower end of the valve pin 12, and the nozzle gate 80 is in a conical or inverted trapezoidal shape.

[0067] The system for controlling the stroke of the valve pin uses a mechanical limiting device to determine the end limit position of the stroke of the valve pin 12. That is, the valve pin 12 colliding with the nozzle gate 80 such as a conical valve pin or the oil cylinder piston 14 itself colliding with the body of the oil cylinder 10 itself is used as a reference.

[0068] Combined with Figure 2As shown, three oil cylinders 10a, 10b, and 10c are connected in parallel to the reversing valve 40.

[0069] Several valve needles 12a, 12b, and 12c (three in this example) are controlled by three oil cylinders 10a, 10b, and 10c respectively. These valve needles are connected to the auxiliary tank 60 through the branch of the first pipeline 20 and the second pipeline 22, and the liquid is transported through the branch. The volume of the fluid flowing in the loop will be optimized proportionally, and the corresponding volume of fluid is injected into each oil cylinder.

[0070] Of course, even in a system where multi-stage pistons and / or multiple chambers are envisaged for the oil cylinders and / or the auxiliary tank, the present invention can be applied without significant modification.

[0071] Combined with Figure 3 As shown, multiple valve needles can be controlled simultaneously on the oil cylinder 10.

[0072] Embodiment 2

[0073] The difference between this embodiment and Embodiment 1 lies in the inner cavity volume adjustment assembly 7, and the others are the same.

[0074] Combined with Figure 5 As shown, the movable sealing plate 70 and the adjustment knob 74 are sleeved on the piston rod 65, and an oil seal is provided between the adjustment knob 74 and the piston rod 65.

[0075] The movable sealing plate adjustment assembly 72 includes an electric assist cylinder 76 fixed on the outer wall of the auxiliary tank 60, and the output end of the electric assist cylinder 76 passes through the auxiliary tank 60 and is connected to the movable sealing plate 70.

[0076] Furthermore, the inner end of the piston rod 65 is connected and integrally formed with the auxiliary piston 64.

[0077] The left liquid inlet and outlet 60a is arranged at one end of the auxiliary piston 64 located in the left chamber 66a, and is connected to the first joint 65a on the outer end of the piston rod 65 through the first liquid guide channel 61a. The right liquid inlet and outlet 60b is arranged at one end of the auxiliary piston 64 located in the left chamber 66a, and is connected to the second joint 65b on the outer end of the piston rod 65 through the second liquid guide channel 61b.

[0078] In this embodiment, since the inner cavity volume adjustment assembly 7 includes two movable sealing plates 70 and an electric power-assisted cylinder 76, the output end of the electric power-assisted cylinder 76 penetrates through the auxiliary tank 60 and is connected to the movable sealing plate 70. The left liquid inlet and outlet 60a is connected to the first joint 65a on the outer end of the piston rod 65 through the first liquid guiding channel 61a, and thus the left chamber 66a is connected to the upper cavity 18a. The volume of the left chamber 66a can be adjusted by the action of the movable sealing plate 70. The right liquid inlet and outlet 60b is connected to the second joint 65b on the outer end of the piston rod 65 through the second liquid guiding channel 61b, and thus the right chamber 66b is connected to the lower cavity 18b. The volume of the right chamber 66b can be adjusted by the action of the movable sealing plate 70. This embodiment can not only adjust the overall volume change of the inner cavity 66, but also more precisely adjust the volume changes of the left chamber 66a and the right chamber 66b. Meanwhile, the valve needle 12 moves more precisely and the fluid loss is smaller.

[0079] Embodiment 3

[0080] This embodiment is a system for controlling the stroke of the valve needle according to Embodiment 1, and provides a method for controlling the stroke of the valve needle, the steps are as follows:

[0081] S1. One end of the valve needle 12 is installed on the valve needle fixing structure 15 at the outer end of the oil cylinder piston 14;

[0082] S2. The hydraulic power mechanism 5 supplies or extracts liquid to / from the upper cavity 18a and the lower cavity 18b of the oil cylinder 10 through the first pipeline 20 and the second pipeline 22;

[0083] S3. Adjust the total liquid supply amount of the upper cavity 18a or the lower cavity 18b through the stroke adjustment mechanism 6.

[0084] Among them, the valve needle 12 starts to move from the closed position, and no molten material passes through the nozzle 13 during this period. When the valve needle 12 reaches the starting position, molten material passes through the nozzle 13 during this period. Since the movement of the fluid is linear, the oil cylinder piston 14 moves linearly in the oil cylinder cavity 18, and thus the connected valve needle 12 also moves. The movement of the valve needle 12 is controlled by injecting a predetermined amount of liquid into the oil cylinder cavity 18 or extracting liquid from the oil cylinder cavity 18. Since the displacement amount is linear, the total amount of fluid injected into or extracted from the oil cylinder cavity 18 in advance will determine the displacement amount of the valve needle.

[0085] The stroke adjustment mechanism 6 includes an auxiliary tank 60 connected to the oil cylinder cavity 18, and the predetermined fluid amount corresponds to the predetermined change amount of the fluid contained in the inner cavity 66. This method is applicable to both filling the oil cylinder cavity 18 and emptying the oil cylinder cavity 18.

[0086] By transferring a certain amount of fluid from the auxiliary tank 60 into the oil cylinder cavity 18, the valve needle 12 is moved from the open position of the nozzle 13 to the closed position accordingly. By transferring a certain amount of fluid from the oil cylinder cavity 18 into the auxiliary tank 60, the valve needle 12 is moved from the closed position of the nozzle 13 to the open position accordingly. The valve needle 12 can be fully opened, fully closed, or stay at any position between open and closed.

[0087] By subtracting the volume of a certain amount of fluid Vc from the fluid in the oil cylinder cavity 18, the displacement of the oil cylinder piston 14 is obtained. This displacement is proportional to Vc and is precise. Similarly, by extracting a certain volume of fluid Vt from the auxiliary tank 60 and injecting it into the oil cylinder cavity 18, the result is that the oil cylinder piston 14 moves in the opposite direction with an accurate displacement that is proportional to Vt.

[0088] The amounts of Vc and Vt are determined by the volume change of the inner cavity 66 in the auxiliary tank 60. The inner cavity 66 has a variable volume and can receive the volume Vc and discharge the volume Vt. After the liquid is discharged, the minimum volume that the cavity of the auxiliary tank can reach is called Vmin, and the unit can be cm3. After introducing the liquid into the auxiliary tank chamber, the maximum volume that the auxiliary tank chamber can reach is called Vmax, and the unit can be cm3.

[0089] That is: Vmax = Vmin + Vt and / or Vmin = Vmax - Vc.

[0090] Vmax is adjustable to determine the volume change of the inner cavity 66, thereby determining Vc and Vt. Vmin can be zero, but it doesn't have to be zero. That is, the inner cavity 66 doesn't necessarily reach zero volume after discharging Vt and can contain the remaining fluid. Preferably, Vc = Vt to make the movement of the valve needle periodic.

[0091] In step S3, the volume of the inner cavity 66 of the auxiliary tank 60 is adjusted by the inner cavity volume adjustment assembly 7, thereby adjusting the total liquid supply volume of the upper cavity 66a or the lower cavity 66b.

[0092] Adjust / change the stroke of the valve needle 12 as needed by changing the values of Vc and Vt, preferably by changing Vmax and / or Vmin. That is, the amount of the liquid is determined by adjusting the maximum change in the volume of the auxiliary fuel tank cavity. Adjust the values of Vmax and / or Vmin through the inner cavity volume adjustment assembly 7.

[0093] The inner cavity 66 is modified by moving the movable sealing plate 70, thereby defining the volume of the auxiliary tank 60 occupied by a predetermined amount of fluid. When the fluid is transferred from the inner cavity 66 to the oil cylinder cavity 18, the linear position of the auxiliary piston 64 will be detected. By using the proportional relationship of the position change of the auxiliary piston 64, the end position of the stroke of the valve needle 12 is determined by adjusting the stroke of the auxiliary piston 64. The fluid transfer between the auxiliary tank 60 and the oil cylinder cavity 18 moves with the movement of the auxiliary piston 64, and the position of the valve needle 12 also changes accordingly.

[0094] The specific embodiments described herein are merely illustrative of the spirit of the present invention. Those skilled in the art to which the present invention pertains can make various modifications or supplements to the described specific embodiments or use similar ways of substitution, but will not deviate from the spirit of the present invention or exceed the scope defined by the appended claims.

[0095] Although terms such as hydraulic power mechanism 5, through the reversing valve 40, oil cylinder 10, cylinder housing 16, oil cylinder cavity 18, oil cylinder piston 14, upper cavity 18a, lower cavity 18b, valve needle 12, valve needle fixing structure 15, first oil passage 19a, second oil passage 19b, first pipeline 20, second pipeline 22, stroke adjusting mechanism 6, auxiliary tank 60, inner cavity 66, left chamber 66a, right chamber 66b, auxiliary piston 64, piston rod 65, inner cavity volume adjusting assembly 7, left liquid inlet and outlet 60a, right liquid inlet and outlet 60b, movable sealing plate 70, sealing plate adjusting assembly 72, adjusting knob 74, electric assist cylinder 76, first liquid guiding channel 61a, first joint 65a, second liquid guiding channel 61b, second joint 65b, stroke limiting assembly 68, flow regulating valve 30, flow regulating valve 32, connecting seat 11, hot runner mold 90, fluid channel 92, valve needle mounting hole 94, nozzle 13, limiting flow blocking structure 8, nozzle gate 80, oil cylinder 10a, oil cylinder 10b, oil cylinder 10c, valve needle 12a, valve needle 12b, valve needle 12c, etc. are used more in this article, the possibility of using other terms is not excluded. The use of these terms is only for more conveniently describing and explaining the essence of the present invention, and interpreting them as any kind of additional limitation is contrary to the spirit of the present invention.

Claims

1. A system for controlling the stroke of a valve needle, comprising a hydraulic power mechanism (5), the hydraulic power mechanism (5) being connected to at least one oil cylinder (10) through a reversing valve (40), the oil cylinder (10) including a cylinder housing (16), an oil cylinder cavity (18) being provided in the cylinder housing (16), the oil cylinder cavity (18) being separated into an upper cavity (18a) and a lower cavity (18b) by a T-shaped oil cylinder piston (14), and the outer end of the oil cylinder piston (14) passing through the cylinder housing (16), a valve needle fixing structure (15) capable of mounting a valve needle (12) being provided at the outer end of the oil cylinder piston (14), a first oil port (19a) of the upper cavity (18a) and a second oil port (19b) of the lower cavity (18b) being respectively connected to the reversing valve (40) through a first pipeline (20) and a second pipeline (22), characterized in that, A stroke adjustment mechanism (6) for storing hydraulic oil and capable of assisting in controlling the working stroke of the cylinder piston (14) is provided on the first pipeline (20) or the second pipeline (22); the stroke adjustment mechanism (6) includes an auxiliary tank (60), an inner cavity (66) is provided in the auxiliary tank (60), an auxiliary piston (64) capable of dividing the inner cavity (66) into a left chamber (66a) and a right chamber (66b) is provided in the inner cavity (66), the outer end of the piston rod (65) of the auxiliary piston (64) penetrates the housing of the auxiliary tank (60), and an inner cavity volume adjustment assembly (7) capable of adjusting the volume of the inner cavity (66) is provided between the auxiliary piston (64) and the auxiliary tank (60), and a left liquid inlet / outlet (60a) and a right liquid inlet / outlet (60b) respectively communicating with the left chamber (66a) and the right chamber (66b) are further provided on the auxiliary tank (60); the inner cavity volume adjustment assembly (7) includes a movable sealing plate (70) capable of axially moving in the left chamber (66a) and / or the right chamber (66b), the outer wall of the movable sealing plate (70) is slidably and sealingly connected with the inner wall of the inner cavity (66), and a sealing plate adjustment assembly (72) capable of adjusting the axial position of the movable sealing plate (70) is provided between the movable sealing plate (70) and the auxiliary tank (60); the sealing plate adjustment assembly (72) includes an adjustment knob (74), and the adjustment knob (74) penetrates the auxiliary tank (60) and is screwed thereto.

2. The system for controlling the valve needle stroke according to claim 1, characterized in that, A stroke limit assembly (68) capable of limiting the linear movement stroke of the auxiliary piston (64) is provided between the auxiliary piston (64) and the auxiliary tank (60).

3. The system for controlling the valve needle stroke according to claim 1, characterized in that Flow regulating valves (30, 32) are provided between the reversing valve (40) and the stroke adjustment mechanism (6) and the cylinder (10), and the flow regulating valves (30, 32) are arranged on the corresponding first pipeline (20) and second pipeline (22).

4. The system for controlling the valve needle stroke according to claim 1, characterized in that, The cylinder (10) is fixed on the hot runner mold (90) through a connecting seat (11), an inverted L-shaped fluid passage (92) is provided on the hot runner mold (90), the valve needle (12) is arranged in the fluid passage (92) through a valve needle mounting hole (94), a nozzle (13) is provided at the lower end of the fluid passage (92), and a limit flow-blocking structure (8) is provided between the nozzle (13) and the valve needle (12).

5. The system for controlling the valve needle stroke according to claim 1, characterized in that, Three cylinders (10a, 10b, 10c) are connected in parallel to the reversing valve (40).

6. A method for controlling the stroke of a valve needle, characterized in that, It is realized by any one of claims 1-5, and the steps are as follows: S1. One end of the valve needle (12) is mounted on the valve needle fixing structure (15) at the outer end of the cylinder piston (14); S2. The hydraulic power mechanism (5) supplies or extracts liquid to / from the upper cavity (18a) and the lower cavity (18b) of the cylinder (10) through the first pipeline (20) and the second pipeline (22); S3. Adjust the total liquid supply volume of the upper cavity (18a) or the lower cavity (18b) through the stroke adjustment mechanism (6); in step S3, adjust the volume of the inner cavity (66) of the auxiliary tank (60) through the inner cavity volume adjustment component (7), so as to adjust the total liquid supply volume of the upper cavity (18a) or the lower cavity (18b).

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