Hydraulic cylinder for sequential telescoping, sequential hydraulic system and its control method

Abstract

The present invention relates to a hydraulic cylinder for sequential telescoping, comprising a cylinder block, on which a first oil port and a second oil port are provided; a connecting seat, on which a third oil port and a fourth oil port are provided; a moving member is movably inserted on the cylinder block, the moving member includes a sequential piston and a piston rod, the sequential piston and the connecting seat are respectively fixed at both ends of the piston rod; a first oil passage is provided on the moving member, the first oil passage communicates with the first oil port and the fourth oil port respectively, and is equipped with a first one-way valve; a second oil passage communicates with the second oil port and the third oil port respectively, and is equipped with a second one-way valve; a third oil passage communicates with the third oil port; when in the fully retracted state, the third oil passage is not communicated with the second oil port; when in the extended state, the third oil passage is not communicated with the second oil port; when in the fully extended state, the third oil passage is communicated with the second oil port. This hydraulic cylinder does not require external sequential control, has a simple structure, high versatility, a wide application range, stable and reliable action sequence, small pressure loss, low cost, and is structurally compact and convenient to install.

Description

Technical Field

[0001] The invention relates to a hydraulic cylinder, in particular to a hydraulic cylinder for sequential extension and retraction, a sequential hydraulic system and a control method thereof. Background Art

[0002] In construction machinery, we often see multiple groups of hydraulic cylinders of actuators acting in a predetermined order. For example, multi-stage boom cranes and other equipment generally use multiple groups of hydraulic cylinders to work in conjunction, so that each level of cylinder can be extended or retracted in sequence from the first cylinder to the end cylinder. At present, there are three main control methods for the sequential action of hydraulic cylinders: one is area difference control, which has low cost and simple structure, but the area of ​​the hydraulic cylinder that extends first is larger than that of the hydraulic cylinder that extends later, and the area of ​​the rod cavity of the hydraulic cylinder that retracts first is larger than that of the hydraulic cylinder that retracts later, which has great limitations in use; the second is sequential valve control, which controls the order of extension and retraction of hydraulic cylinders by adding sequential valves in the oil circuit and adjusting the opening pressure of the sequential valves. When the pressure difference between the hydraulic cylinders is small, the action sequence will be confused. The larger the pressure difference of the sequential valve, the better the reliability of the sequential action, and at the same time, the greater the pressure loss, so it is not suitable for the sequential control of multiple groups of hydraulic cylinders. The third is mechanical control. This control method mainly controls the on-and-off of the oil circuit through an external mechanical device to achieve sequential action of each hydraulic cylinder. This method will not be affected by load pressure, has small pressure loss, does not need to adjust the opening pressure of the valve core, and has good reliability of sequential action. However, the control device needs to be designed according to the installation position of each hydraulic cylinder, and its versatility is poor. Summary of the invention

[0003] In order to solve the above problems, the present invention provides a hydraulic cylinder for sequential extension and retraction which realizes sequential extension and retraction of the hydraulic cylinder by setting the internal oil circuit of the hydraulic cylinder, does not require external sequential control, has simple structure, high versatility, wide application range, stable and reliable action sequence, small pressure loss, and low cost. The specific technical scheme is as follows:

[0004] Hydraulic cylinder for sequential control, comprising: a cylinder block, a first oil port is provided at the bottom of the cylinder block, and a second oil port is provided at the top of the cylinder block; a connecting seat, a third oil port and a fourth oil port are provided on the connecting seat; a moving member, the moving member is movably inserted on the cylinder block, the moving member includes a sequential piston and a piston rod, and the sequential piston and the connecting seat are respectively fixed at both ends of the piston rod; a first oil passage, the first oil passage is provided on the moving member, and the first oil passage communicates with the first oil port and the fourth oil port respectively; a first one-way valve, the first one-way valve is installed on the first oil passage; a second oil passage, the second oil passage communicates with the second oil port and the third oil port respectively; a second one-way valve, the second one-way valve is installed on the second oil passage; a third oil passage, the third oil passage communicates with the third oil port; the hydraulic cylinder for sequential control includes a fully retracted state, an extended state, a fully extended state and a retracted state; in the extended state, the first one-way valve is open, the first oil passage is open, the second one-way valve is closed, the second oil passage is blocked, and the third oil passage is not in communication with the second oil port; in the fully extended state, the first one-way valve is open, the first oil passage is open, the second one-way valve is closed, the second oil passage is blocked, and the third oil passage is in communication with the second oil port; in the retracted state, the first one-way valve is closed, the first oil passage is open, the second one-way valve is open, the second oil passage is blocked, and the third oil passage is not in communication with the second oil port; in the fully retracted state, the first one-way valve is open, the first oil passage is open, the second one-way valve is open, the second oil passage is open, and the third oil passage is not in communication with the second oil port.

[0005] Further, a rod body through hole is provided on the piston rod, and the rod body through hole communicates with the third oil port; a first oil passing hole and a second oil passing hole, both of which communicate with the cylinder inner cavity, are provided inside the second oil port; the first oil path includes: a piston through hole provided on the sequential piston, the piston through hole communicating with the first oil port, and the first one-way valve is installed on the piston through hole; and a guide oil pipe fixed inside the piston through hole and located inside the rod body through hole, the guide oil pipe communicating with the first one-way valve and the fourth oil port respectively; the second oil path includes: a second oil hole provided on the sequential piston and located on one side of the second oil port, the second oil hole communicating with the second oil port and the third oil port respectively, and the second one-way valve is installed on the second oil hole; the third oil path includes: a third oil groove provided on the outer circumferential surface of the sequential piston; a sealing ring installed on the outer circumferential surface of the sequential piston and located on both sides of the third oil groove; and a third oil hole provided at the bottom of the third oil groove and communicating with the third oil port; when the piston rod fully extends out, the second oil port, the first oil passing hole, the third oil groove, the third oil hole and the third oil port communicate with each other.

[0006] Further, the outer diameter of the guide oil pipe is smaller than the inner diameter of the piston through hole, the piston through hole communicates with the rod body through hole, and both the second oil hole and the third oil hole communicate with the piston through hole.

[0007] Further, a second oil groove is provided at one end of the sequential piston, a second oil hole is provided at the bottom of the second oil groove, and the second oil groove communicates with the second oil port.

[0008] Further, the first one-way valve includes: a first valve seat with a valve seat through hole provided at one end thereof, the first valve seat being fixed on the piston through hole; a first valve core with a first valve rod provided thereon, the diameter of the first valve rod being smaller than the diameter of the valve seat through hole, the first valve rod being movably inserted into the valve seat through hole, and the length of the first valve rod being greater than the length of the valve seat through hole, the first valve core being used to close or open the valve seat through hole; and a first spring with one end pressing on the first valve core and the other end pressing on the piston through hole.

[0009] Further, a valve seat tapered hole is provided at the other end of the first valve seat, the valve seat tapered hole communicating with the valve seat through hole, and a sealing spherical surface is provided on the first valve core, the sealing spherical surface being arranged opposite to the valve seat tapered hole.

[0010] Further, the second oil passing holes are small holes and are provided in plurality, and the diameter of the second oil passing holes is smaller than the diameter of the sealing ring.

[0011] Sequential hydraulic system, comprising: the hydraulic cylinders for sequential control, with no less than two of the hydraulic cylinders for sequential control being connected in series in sequence; the first-stage first oil port and the first-stage second oil port of the first-stage hydraulic cylinder for sequential telescoping are both used for oil inlet or oil return, the first-stage third oil port of the first-stage hydraulic cylinder for sequential telescoping communicates with the N-stage second oil port of the N-stage hydraulic cylinder for sequential telescoping, the first-stage fourth oil port of the first-stage hydraulic cylinder for sequential telescoping communicates with the N-stage first oil port of the N-stage hydraulic cylinder for sequential telescoping, and the N-stage third oil port and the N-stage fourth oil port of the N-stage hydraulic cylinder for sequential telescoping are both closed.

[0012] Control method for the hydraulic cylinder for sequential control, comprising the following steps: the piston rod starts to extend from the fully retracted state, oil enters through the first oil port, the first check valve opens, the first oil circuit is unblocked, the second check valve closes, the second oil circuit is blocked, and the third oil circuit is not connected to the second oil port; the piston rod continues to extend, oil enters through the first oil port, the first check valve opens, the first oil circuit is unblocked, the second check valve closes, the second oil circuit is blocked, the third oil circuit is not connected to the second oil port, and oil returns through the second oil port; the piston rod extends fully, oil enters through the first oil port, the first check valve opens, the first oil circuit is unblocked, the second check valve closes, the second oil circuit is blocked, the third oil circuit communicates with the second oil port, and oil returns through the second oil port; the piston rod continues to retract, oil returns through the first oil port, oil enters through the second oil port, the first check valve closes, the first oil circuit is blocked, the second check valve opens, the second oil circuit is unblocked, the third oil circuit is not connected to the second oil port, until the piston rod retracts fully.

[0013] Compared with the prior art, the present invention has the following beneficial effects:

[0014] The hydraulic cylinder for sequential telescoping provided by the present invention realizes the sequential telescoping of the hydraulic cylinder through the setting of the internal oil circuit of the hydraulic cylinder, without external sequential control, and has the advantages of simple structure, high versatility, wide application range, stable and reliable action sequence, small pressure loss, low cost, and being structurally compact and easy to install.

[0015] The sequential hydraulic system does not require complex external control, can realize sequential telescoping stably and reliably, has a simple external oil circuit, and is convenient to use. Brief Description of the Drawings

[0016] Figure 1 is a cross-sectional view of the hydraulic cylinder for sequential control;

[0017] Figure 2 is a cross-sectional view of the first check valve;

[0018] Figure 3 is a partial structural schematic diagram of the hydraulic cylinder for sequential control in the fully retracted state;

[0019] Figure 4It is a partial structural schematic diagram when the hydraulic cylinder for sequential control is in the fully extended state;

[0020] Figure 5 It is a structural schematic diagram for explaining the sequential hydraulic system using three hydraulic cylinders for sequential control, and the piston rods of the three hydraulic cylinders for sequential control are all in the fully retracted state;

[0021] Figure 6 It is Figure 5 a structural schematic diagram when the piston rod of the primary hydraulic cylinder for sequential control extends;

[0022] Figure 7 It is Figure 5 a structural schematic diagram when the piston rods of the three hydraulic cylinders for sequential control are all fully extended. Specific embodiments

[0023] The present invention will be further described below with reference to the accompanying drawings.

[0024] Embodiment 1

[0025] As Figures 1 to 4 shown, the hydraulic cylinder for sequential control includes: a cylinder block 1, a first oil port 11 is provided at the bottom of the cylinder block 1, and a second oil port 12 is provided at the top of the cylinder block 1; a connecting seat 4, a third oil port 43 and a fourth oil port 44 are provided on the connecting seat 4; a moving member, the moving member is movably inserted on the cylinder block 1, the moving member includes a sequential piston 2 and a piston rod 3, the sequential piston 2 and the connecting seat 4 are respectively fixed at both ends of the piston rod 3; a first oil circuit, the first oil circuit is provided on the moving member, and the first oil circuit communicates with the first oil port 11 and the fourth oil port 44 respectively; a first one-way valve 21, the first one-way valve 21 is installed on the first oil circuit; a second oil circuit, the second oil circuit communicates with the second oil port 12 and the third oil port 43 respectively; a second one-way valve 22, the second one-way valve 22 is installed on the second oil circuit; a third oil circuit, the third oil circuit communicates with the third oil port 43; the hydraulic cylinder for sequential control includes an extended state, a fully extended state, a retracted state and a fully retracted state; in the extended state, the first one-way valve 21 is opened, the first oil circuit is connected, the second one-way valve 22 is closed, the second oil circuit is not connected, and the third oil circuit is not connected to the second oil port 12; in the fully extended state, the first one-way valve 21 is opened, the first oil circuit is connected, the second one-way valve 22 is closed, the second oil circuit is not connected, and the third oil circuit is connected to the second oil port 12; in the retracted state, the first one-way valve 21 is closed, the first oil circuit is not connected, the second one-way valve 22 is opened, the second oil circuit is connected, and the third oil circuit is not connected to the second oil port 12; in the fully retracted state, the first one-way valve 21 is opened, the first oil circuit is connected, the second one-way valve 22 is opened, the second oil circuit is connected, and the third oil circuit is not connected to the second oil port 12.

[0026] A rod body through hole 31 is provided on the piston rod 3, and the rod body through hole 31 communicates with the third oil port 43; inside the second oil port 12, a first oil passing hole 121 and a second oil passing hole 122 that both communicate with the inner cavity of the cylinder block 1 are provided; the first oil circuit includes: a piston through hole 25 provided on the sequential piston 2, the piston through hole 25 communicates with the first oil port 11, and a first one-way valve 21 is installed on the piston through hole 25; and a guide oil pipe 5 fixed inside the piston through hole 25 and located inside the rod body through hole 31, the guide oil pipe 5 communicates with the first one-way valve 21 and the fourth oil port 44 respectively; the second oil circuit includes: a second oil hole 222 provided on the sequential piston 2 and located on one side of the second oil port 12, the second oil hole 222 communicates with the second oil port 12 and the third oil port 43 respectively, and a second one-way valve 22 is installed on the second oil hole 222; the third oil circuit includes: a third oil groove 231 provided on the outer circumferential surface of the sequential piston 2; a sealing ring 26 installed on the outer circumferential surface of the sequential piston 2 and located on both sides of the third oil groove 231; and a third oil hole 232 provided at the bottom of the third oil groove 231 and communicating with the third oil port 43; when the piston rod 3 fully extends, the second oil port 12, the first oil passing hole 121, the third oil groove 231, the third oil hole 232 and the third oil port 43 communicate with each other.

[0027] The piston through hole 25 is provided at the center of the sequential piston 2 and is a stepped hole. The outer diameter of the guide oil pipe 5 is smaller than the inner diameter of the piston through hole 24, and both the third oil hole 232 and the second oil hole 222 communicate with the piston through hole 25.

[0028] The key points for the sequential telescopic hydraulic cylinder lie in the second oil port 12, the first oil passing hole 121, the third oil groove 231, the third oil hole 232 and the third oil port 43. When the piston rod 3 extends or retracts, it is the same as an ordinary hydraulic cylinder. However, when the sequential piston 2 moves to the top of the cylinder block 1, the first oil passing hole 121, the third oil groove 231, the third oil hole 232, the piston through hole 25 and the second oil port 12 communicate with each other. At this time, the hydraulic oil of the next stage can return, so that the next stage of the hydraulic cylinder can extend to achieve sequential control.

[0029] When oil enters the first oil port 11 to extend the piston rod 3, the hydraulic oil can enter the hydraulic cylinder of the next stage through the first oil circuit, while the hydraulic oil of each stage of the hydraulic cylinder can only return through the second oil port 12 of the first hydraulic cylinder. That is, the first oil circuit is conductive when the piston rod 3 is extended, but is blocked when the piston rod 3 is retracted. The first oil circuit is unblocked only when the piston rod 3 is fully retracted. In other words, the hydraulic oil is unblocked from the first oil hole to the fourth oil port 44, but is blocked from the fourth oil port 44 to the first oil port 11. The hydraulic oil is unblocked from the fourth oil port 44 to the first oil port 11 only when the piston rod 3 is fully retracted. When the hydraulic oil flows from the second oil port 12 to the third oil port 43, the second one-way valve 22 is opened and the second oil circuit is open. However, when the hydraulic oil flows from the third oil port 43 to the second oil hole 222, the second one-way valve 22 is closed and the second oil circuit is blocked. Only when the sequential piston 2 moves to the top of the cylinder body 1, that is, the third oil circuit is connected, can the hydraulic oil enter the second oil port 12 from the third oil port 43 to realize oil return. Therefore, only after the piston rod 3 of the first-level sequential telescopic hydraulic cylinder is fully extended, the piston rod 3 of the second-level sequential telescopic hydraulic cylinder can be extended, and then the piston rods 3 of the sequential telescopic hydraulic cylinders of each stage are extended in sequence to realize sequential extension.

[0030] When the first oil port 11 takes in oil for retraction, the hydraulic oil blocks the first one-way valve 21, and the first oil path of the hydraulic oil entering the first oil port 11 from the fourth oil port 44 is blocked. Therefore, except for the sequential piston 2 of the first stage of the sequential telescopic hydraulic cylinder that can be retracted, the sequential pistons 2 of the remaining cylinder bodies 1 cannot move, thereby achieving sequential retraction.

[0031] The outer diameter of the oil guide pipe 5 is smaller than the inner diameter of the piston through hole 25 . The piston through hole 25 is communicated with the rod body through hole 31 . The second oil hole 222 and the third oil hole 232 are both communicated with the piston through hole 25 .

[0032] A second oil groove 221 is provided at one end of the sequential piston 2 , a second oil hole 222 is provided at the bottom of the second oil groove 221 , and the second oil groove 221 is communicated with the second oil port 12 .

[0033] The second oil hole 222 is arranged radially, which facilitates the installation of the second check valve 22 and makes the structure compact. The second oil groove 221 facilitates the radial arrangement of the second oil hole 222 and ensures that the second oil hole 222 communicates with the rod chamber of the cylinder body.

[0034] The first one-way valve 21 includes: a first valve seat 211, one end of which is provided with a valve seat through hole 212, and the first valve seat 211 is fixed on the piston through hole 25; a first valve core 213, on which is provided a first valve stem 216, the diameter of the first valve stem 216 is smaller than the diameter of the valve seat through hole 212, the first valve stem 216 is movably inserted into the valve seat through hole 212, and the length of the first valve stem 216 is greater than the length of the valve seat through hole 212, and the first valve core 213 is used to close or open the valve seat through hole 212; a first spring 217, one end of the first spring 217 is pressed on the first valve core 213, and the other end is pressed on the piston through hole 25.

[0035] The first valve stem 216 opens the first check valve 21 when the sequential piston 2 is at the bottom of the cylinder. The spring force of the first spring 217 is relatively small, which facilitates the opening of the first check valve 21 and ensures the reliability of sequential extension. Usually, the pressure of 0.4-0.8MPa can open it.

[0036] When the first valve stem 216 is in a fully retracted state, the first oil circuit is opened, so that the hydraulic oil can enter each hydraulic cylinder, thereby making the sequential extension continuous and smooth without obvious pauses.

[0037] A valve seat tapered hole 215 is provided at the other end of the first valve seat 211 . The valve seat tapered hole 215 is communicated with the valve seat through hole 212 . A sealing spherical surface 214 is provided on the first valve core 213 . The sealing spherical surface 214 is arranged opposite to the valve seat tapered hole 215 .

[0038] The spherical surface and the conical surface have good sealing performance and long service life.

[0039] The second oil holes 122 are small holes, and there are multiple of them. The diameter of the second oil holes 122 is smaller than the diameter of the sealing ring 26. The second oil holes 122 are arranged in an array, and the hole diameter is 2-5mm, so that the sealing ring 26 will not be scratched when passing through the second oil holes 222, thereby ensuring the service life of the sealing ring 26.

[0040] A guide sleeve is arranged on the top of the cylinder body 1, and the piston rod 3 is movably inserted in the guide sleeve.

[0041] A control method for a hydraulic cylinder for sequential control, comprising the following steps:

[0042] The piston rod 3 starts to extend from the fully retracted state, oil enters the first oil port 11, the first one-way valve 21 opens, the first oil path is connected, the second one-way valve 22 is closed, the second oil path is blocked, and the third oil path is blocked from the second oil port 12;

[0043] The piston rod 3 continues to extend, oil enters the first oil port 11, the first one-way valve 21 opens, the first oil circuit is connected, the second one-way valve 22 is closed, the second oil circuit is blocked, the third oil circuit is blocked from the second oil port 12, and oil returns from the second oil port 12;

[0044] The piston rod 3 fully extends, the first oil port 11 admits oil, the first one-way valve 21 opens, the first oil circuit is open, the second one-way valve 22 closes, the second oil circuit is blocked, the third oil circuit communicates with the second oil port 12, and the second oil port 12 returns oil.

[0045] The piston rod 3 continuously retracts, the first oil port 11 returns oil, the second oil port 12 admits oil, the first one-way valve 21 closes, the first oil circuit is blocked, the second one-way valve 22 opens, the second oil circuit is open, the third oil circuit is not connected to the second oil port 12 until the piston rod 3 fully retracts.

[0046] Embodiment Two

[0047] Based on the above Embodiment One, a sequential hydraulic system includes: no less than two sequentially connected hydraulic cylinders for sequential telescoping. The first-stage first oil port and the first-stage second oil port of the first-stage hydraulic cylinder for sequential telescoping are both used for admitting oil or returning oil. The first-stage third oil port of the first-stage hydraulic cylinder for sequential telescoping communicates with the N-stage second oil port of the N-stage hydraulic cylinder for sequential telescoping. The first-stage fourth oil port of the first-stage hydraulic cylinder for sequential telescoping communicates with the N-stage first oil port of the N-stage hydraulic cylinder for sequential telescoping. The N-stage third oil port and the N-stage fourth oil port of the N-stage hydraulic cylinder for sequential telescoping are both closed.

[0048] Taking three sequentially connected hydraulic cylinders for sequential telescoping as an example, the three hydraulic cylinders for sequential telescoping are respectively the first-stage hydraulic cylinder for sequential telescoping, the second-stage hydraulic cylinder for sequential telescoping, and the third-stage hydraulic cylinder for sequential telescoping.

[0049] The first-stage first oil port A1 and the first-stage second oil port A2 of the first-stage hydraulic cylinder for sequential telescoping are both used for admitting oil or returning oil. The first-stage third oil port A3 of the first-stage hydraulic cylinder for sequential telescoping communicates with the second-stage second oil port B2 of the second-stage hydraulic cylinder for sequential telescoping. The first-stage fourth oil port A4 of the first-stage hydraulic cylinder for sequential telescoping communicates with the second-stage first oil port B1 of the second-stage hydraulic cylinder for sequential telescoping.

[0050] The second-stage third oil port B3 of the second-stage hydraulic cylinder for sequential telescoping communicates with the third-stage second oil port C2 of the third-stage hydraulic cylinder for sequential telescoping. The second-stage fourth oil port B4 of the second-stage hydraulic cylinder for sequential telescoping communicates with the third-stage first oil port C1 of the third-stage hydraulic cylinder for sequential telescoping. The third-stage third oil port C3 and the third-stage fourth oil port C4 of the third-stage hydraulic cylinder for sequential telescoping are both closed.

[0051] The rodless cavity is between the sequential piston and the first oil port, and the rod cavity is between the sequential piston and the second oil port.

[0052] Hereinafter, the first-stage hydraulic cylinder for sequential telescoping, the second-stage hydraulic cylinder for sequential telescoping, and the third-stage hydraulic cylinder for sequential telescoping are respectively abbreviated as the first-stage cylinder, the second-stage cylinder, and the third-stage cylinder.

[0053] Extension stage:

[0054] At this time, all the piston rods of the sequential telescopic hydraulic cylinders are in a fully retracted state. When hydraulic oil is connected to the first first oil port A1 of the first-stage cylinder, the hydraulic oil enters the rodless cavity of the first-stage cylinder. The hydraulic oil in the rodless cavity of the first-stage cylinder passes through the first one-way valve of the first stage, the first-stage oil pipe, and the first fourth oil port A4 of the first stage, and then is introduced into the second first oil port B1 of the second-stage cylinder through an external oil pipe. The hydraulic oil enters the rodless cavity of the second-stage cylinder. The hydraulic oil passes through the first one-way valve of the second stage, the second-stage oil pipe, and the second fourth oil port B4 of the second stage, and then enters the third first oil port C1 of the third-stage cylinder through an external oil pipe. The hydraulic oil enters the rodless cavity of the third-stage cylinder. Then the hydraulic oil passes through the first one-way valve of the third stage and enters the third-stage oil pipe. Since the third fourth oil port C4 is closed, the hydraulic oil stops in the third-stage oil pipe.

[0055] It can be seen from this that when hydraulic oil enters the rodless cavity of the first stage, the hydraulic oil can enter the rodless cavities of each stage of the hydraulic cylinder. After the hydraulic oil enters the rodless cavities of each stage, it drives the piston rods of each stage of the hydraulic cylinder to extend. The hydraulic oil in the rodless cavities of each stage of the hydraulic cylinder will surely be discharged through the first second oil port A2 of the first-stage cylinder. Obviously, the hydraulic oil in the rodless cavity of the first-stage cylinder can be discharged through the first second oil port A2, and the first piston rod can extend smoothly. At the same time, the second piston rod of the second-stage cylinder also has a tendency to extend. The hydraulic oil in the rodless cavity of the second-stage cylinder needs to be discharged from the second second oil port B2, and enters the inner cavity of the first-stage oil pipe through the external oil pipe and the first third oil port A3 of the first-stage cylinder. The first second one-way valve is closed, that is, when the hydraulic oil enters the first second oil port A2 from the first third oil port A3, the first second one-way valve intercepts the flow. At this time, the first third oil hole is also not connected to the first second oil port A2, that is, the first third oil path is blocked, and the hydraulic oil in the rodless cavity of the second-stage cylinder cannot complete the oil return through the rodless cavity of the first-stage cylinder. Therefore, the second piston rod of the second-stage cylinder cannot extend.

[0056] When the piston rod of the first-stage cylinder is fully extended, the first third oil groove on the first-stage sequential piston corresponds to the first first oil hole on the first-stage cylinder block, as Figure 4 shown. At this time, the hydraulic oil in the through hole of the first rod body of the first piston rod can be discharged from the first second oil port A2 through the first third oil groove and the first first oil hole. The second piston rod of the second-stage cylinder can then extend. At this time, the oil return flow path of the rodless cavity of the third-stage cylinder needs to wait until the second piston rod of the second-stage cylinder is fully extended before it can be opened. By analogy, the sequential extension of the piston rods can be completed.

[0057] Retraction stage:

[0058] At this time, the piston rods of each hydraulic cylinder are in a fully extended state, and the third oil circuit of each hydraulic cylinder is open. When hydraulic oil is introduced into the first-stage second oil port A2 of the first-stage cylinder, the hydraulic oil enters the rod cavity of the first-stage cylinder and the through-hole in the rod body of the first-stage piston rod. At the same time, the hydraulic oil can also communicate with the first-stage third oil port A3 through the first-stage second check valve. The hydraulic oil passes through the first-stage third oil port A3 and the external pipeline and enters the second-stage second oil port B2 of the second-stage cylinder, and then enters the rod cavity of the second-stage cylinder. Furthermore, the hydraulic oil in the rod cavity of the second-stage cylinder can enter the rod cavity of the third-stage cylinder through the second oil circuit of the second-stage cylinder. It can be seen that when hydraulic oil is introduced into the first-stage second oil port A2 of the first-stage cylinder, the hydraulic oil can enter the rod cavities of each hydraulic cylinder. After the hydraulic oil enters the rod cavity, it drives the piston rods of each hydraulic cylinder to retract, and the hydraulic oil in the rodless cavities of each stage needs to be discharged from the first-stage first oil port A1 of the first-stage cylinder. Obviously, the hydraulic oil in the rodless cavity of the first-stage cylinder can be discharged from the first-stage first oil port A1, and the first-stage piston rod can retract smoothly. The hydraulic oil in the rodless cavity of the second-stage cylinder passes through the second-stage first oil port B1, the external oil pipe and the first-stage fourth oil port A4 of the first-stage cylinder, and then enters the first-stage guide oil pipe of the first-stage cylinder. At this time, the first-stage first check valve in the first oil circuit of the first stage is closed, that is, the flow from the first-stage fourth oil port A4 to the first-stage first oil hole is blocked by the first-stage first check valve, and the first oil circuit of the first stage is not open. Therefore, the second-stage piston rod of the second-stage cylinder cannot retract. When the first-stage piston rod of the first-stage cylinder moves to the bottom of the first-stage cylinder body or the first-stage cylinder is fully retracted, as Figure 3 shown, the first check valve is pushed open, and the first oil circuit of the first stage is conducted. At this time, the oil return passage of the rodless cavity of the second-stage cylinder of the second-stage cylinder is opened, and the second-stage piston rod can retract. When the second-stage piston rod of the second-stage cylinder reaches the bottom of the cylinder, the second-stage first check valve opens, and the third-stage piston rod of the third-stage cylinder can retract, and so on, and the sequential retraction of the piston rod can be completed.

[0059] The technical principle of the present invention has been described above in conjunction with specific embodiments. These descriptions are only for explaining the principle of the present invention and cannot be construed in any way as a limitation on the protection scope of the present invention. Based on the explanations herein, those skilled in the art can readily conceive of other specific embodiments of the present invention without creative efforts, and these embodiments will fall within the protection scope of the claims of the present invention.

Claims

1. A hydraulic cylinder for sequential control, characterized in that, it comprises: a cylinder block (1), a first oil port (11) is provided at the bottom of the cylinder block (1), and a second oil port (12) is provided at the top of the cylinder block (1); a connecting seat (4), a third oil port (43) and a fourth oil port (44) are provided on the connecting seat (4); a moving member, the moving member is movably inserted on the cylinder block (1), the moving member includes a sequential piston (2) and a piston rod (3), and the sequential piston (2) and the connecting seat (4) are respectively fixed at both ends of the piston rod (3); a first oil circuit, the first oil circuit is provided on the moving member, and the first oil circuit is respectively communicated with the first oil port (11) and the fourth oil port (44); a first one-way valve (21), the first one-way valve (21) is installed on the first oil circuit; a second oil circuit, the second oil circuit is respectively communicated with the second oil port (12) and the third oil port (43); a second one-way valve (22), the second one-way valve (22) is installed on the second oil circuit; a third oil circuit, the third oil circuit is communicated with the third oil port (43); the hydraulic cylinder for sequential control includes an extended state, a fully extended state, a retracted state and a fully retracted state; in the extended state, the first one-way valve (21) is opened, the first oil circuit is communicated, the second one-way valve (22) is closed, the second oil circuit is not communicated, and the third oil circuit is not communicated with the second oil port (12); in the fully extended state, the first one-way valve (21) is opened, the first oil circuit is communicated, the second one-way valve (22) is closed, the second oil circuit is not communicated, and the third oil circuit is communicated with the second oil port (12); in the retracted state, the first one-way valve (21) is closed, the first oil circuit is not communicated, the second one-way valve (22) is opened, the second oil circuit is communicated, and the third oil circuit is not communicated with the second oil port (12); in the fully retracted state, the first one-way valve (21) is opened, the first oil circuit is communicated, the second one-way valve (22) is opened, the second oil circuit is communicated, and the third oil circuit is not communicated with the second oil port (12).

2. The hydraulic cylinder for sequential control according to claim 1, characterized in that, a rod body through hole (31) is provided on the piston rod (3), and the rod body through hole (31) is communicated with the third oil port (43); inside the second oil port (12), a first oil passing hole (121) and a second oil passing hole (122) which are both communicated with the inner cavity of the cylinder block (1) are provided; the first oil circuit includes: a piston through hole (25), the piston through hole (25) is provided on the sequential piston (2), the piston through hole (25) is communicated with the first oil port (11), and the first one-way valve (21) is installed on the piston through hole (25); and a guide oil pipe (5), the guide oil pipe (5) is fixed inside the piston through hole (25) and is located inside the rod body through hole (31), and the guide oil pipe (5) is respectively communicated with the first one-way valve (21) and the fourth oil port (44); The second oil passage includes: A second oil hole (222) which is provided on the sequential piston (2) and is located on one side of the second oil port (12). The second oil hole (222) communicates with the second oil port (12) and the third oil port (43) respectively, and the second one-way valve (22) is installed on the second oil hole (222); The third oil passage includes: A third oil groove (231) which is provided on the outer circumferential surface of the sequential piston (2); A sealing ring (26) which is installed on the outer circumferential surface of the sequential piston (2) and is located on both sides of the third oil groove (231); and A third oil hole (232) which is provided at the bottom of the third oil groove (231) and communicates with the third oil port (43); When the piston rod (3) fully extends, the second oil port (12), the first oil through-hole (121), the third oil groove (231), the third oil hole (232) and the third oil port (43) communicate with each other.

3. The hydraulic cylinder for sequential control according to claim 2, characterized in that the outer diameter of the guide oil pipe (5) is smaller than the inner diameter of the piston through-hole (25). The piston through-hole (25) communicates with the rod body through-hole (31), and both the second oil hole (222) and the third oil hole (232) communicate with the piston through-hole (25).

4. The hydraulic cylinder for sequential control according to claim 2, characterized in that one end of the sequential piston (2) is provided with a second oil groove (221). The bottom of the second oil groove (221) is provided with a second oil hole (222), and the second oil groove (221) communicates with the second oil port (12).

5. The hydraulic cylinder for sequential control according to claim 2, characterized in that The first one-way valve (21) includes: A first valve seat (211) with a valve seat through-hole (212) provided at one end thereof. The first valve seat (211) is fixed on the piston through-hole (25); A first valve core (213) with a first valve rod (216) provided thereon. The diameter of the first valve rod (216) is smaller than the diameter of the valve seat through-hole (212). The first valve rod (216) is movably inserted into the valve seat through-hole (212), and the length of the first valve rod (216) is greater than the length of the valve seat through-hole (212). The first valve core (213) is used to close or open the valve seat through-hole (212); A first spring (217) with one end pressing on the first valve core (213) and the other end pressing on the piston through-hole (25).

6. The hydraulic cylinder for sequential control according to claim 5, characterized in that The other end of the first valve seat (211) is provided with a valve seat tapered hole (215), the valve seat tapered hole (215) communicates with the valve seat through hole (212), a sealing spherical surface (214) is provided on the first valve core (213), and the sealing spherical surface (214) is arranged opposite to the valve seat tapered hole (215).

7. The hydraulic cylinder for sequential control according to claim 2, wherein, the second oil through hole (122) is a small hole and there are multiple of them, and the diameter of the second oil through hole (122) is smaller than the diameter of the sealing ring (26).

8. A sequential hydraulic system, wherein, comprising: the hydraulic cylinder for sequential control according to any one of claims 1 to 7, the hydraulic cylinders for sequential control are not less than two and are connected in series in sequence; both the first oil port and the second oil port of the first-stage hydraulic cylinder for sequential telescoping are used for oil inlet or oil return, the third oil port of the first-stage hydraulic cylinder for sequential telescoping communicates with the second oil port of the N-stage hydraulic cylinder for sequential telescoping, the fourth oil port of the first-stage hydraulic cylinder for sequential telescoping communicates with the first oil port of the N-stage hydraulic cylinder for sequential telescoping, and the third oil port and the fourth oil port of the N-stage hydraulic cylinder for sequential telescoping are both closed.

9. A control method for a hydraulic cylinder for sequential control, for the hydraulic cylinder for sequential telescoping according to claim 1, wherein, comprising the following steps: the piston rod (3) starts to extend from the fully retracted state, the first oil port (11) intakes oil, the first check valve (21) opens, the first oil circuit is unblocked, the second check valve (22) closes, the second oil circuit is blocked, and the third oil circuit is blocked from the second oil port (12); the piston rod (3) continues to extend, the first oil port (11) intakes oil, the first check valve (21) opens, the first oil circuit is unblocked, the second check valve (22) closes, the second oil circuit is blocked, the third oil circuit is blocked from the second oil port (12), and the second oil port (12) returns oil; the piston rod (3) is fully extended, the first oil port (11) intakes oil, the first check valve (21) opens, the first oil circuit is unblocked, the second check valve (22) closes, the second oil circuit is blocked, the third oil circuit communicates with the second oil port (12), and the second oil port (12) returns oil; the piston rod (3) continues to retract, the first oil port (11) returns oil, the second oil port (12) intakes oil, the first check valve (21) closes, the first oil circuit is blocked, the second check valve (22) opens, the second oil circuit is unblocked, the third oil circuit is blocked from the second oil port (12) until the piston rod (3) is fully retracted.

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