Plunger hydraulic cylinder with adjustable stroke buffer

Abstract

The invention relates to the technical field of hydraulic cylinders, in particular to a stroke-adjustable buffering plunger hydraulic cylinder which comprises a cylinder body and a sealing pipe and further comprises a push rod, a piston, an adjusting assembly, a plunger assembly and a fixing assembly, the push rod is connected to the interior of the sealing pipe, the piston is connected to the lower end of the push rod, and oil outlet grooves are formed in the upper side and the lower side of the inner wall of the cylinder body; throttling grooves are formed in the two sides of the oil outlet groove, adjusting blocks are connected into the throttling grooves, and an oil outlet is formed in the front side of the outer wall of the cylinder body. The plunger assembly is arranged, the length of the plunger assembly is changed through the adjusting assembly, the length of the buffering stroke is changed, then the buffering effect is changed, the cross section of the lower plunger is designed to be funnel-shaped, when the lower plunger moves downwards, the distance between the lower plunger and the inner wall of the oil outlet groove is gradually reduced, and an opening of the oil outlet groove is gradually reduced; the buffering force applied to the piston is gradually increased, so that the buffering smoothness is improved, and vibration caused by sudden change of the buffering force applied to the piston is avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of hydraulic cylinders, and particularly to a plunger hydraulic cylinder with adjustable stroke buffering. Background Art

[0002] A plunger hydraulic cylinder, also known as a ram cylinder, is a structural form of a hydraulic cylinder that can only achieve linear motion. Reverse motion usually relies on external forces such as self-weight, spring force, or external load to achieve. It mainly consists of a cylinder bottom, a cylinder barrel, a plunger, a guide sleeve, seals, limiters, etc. In order to prevent the piston from generating huge impacts and vibrations when hitting the cylinder head or other components at the end of the stroke, a buffering device is set at the end of the stroke.

[0003] The buffering device of a plunger hydraulic cylinder usually consists of a buffer plunger, a buffer chamber, a throttle hole, etc. When the push rod moves close to the end of the stroke and enters the buffering stroke stage, the buffer plunger will first enter the buffer chamber. At this time, the hydraulic fluid in the buffer chamber is compressed, generating a buffering force. When being extruded, the hydraulic fluid can only be extruded from the throttle small hole or the throttle ring gap between the buffer plunger and the hole groove, so as to force the moving plunger to decelerate and brake through back pressure, thereby achieving buffering, and the buffering force and buffering effect are adjusted by adjusting the size of the throttle hole. For example, in equipment such as cranes and hoists, the hydraulic cylinder is used to drive the lifting and lowering of heavy objects. A hydraulic cylinder with an adjustable throttle hole can precisely control the lifting and lowering speed of the load to ensure the safety of operation, avoid damage to the equipment caused by too fast a lowering speed, or affect the work efficiency due to too slow a speed.

[0004] The buffering stroke of a plunger hydraulic cylinder is a part of the hydraulic cylinder stroke, and it is also a stroke where the push rod slows down its movement speed through the buffering device when approaching the end of the stroke.

[0005] When the pressure on the push rod is relatively large, it is necessary to correspondingly increase the buffering force to meet the buffering effect. However, too large a buffering force is likely to cause excessive buffering, resulting in too high a buffering pressure peak near the end point, leading to the phenomenon that the push rod is prone to crosstalk, causing noise and machine vibration, and causing certain damage to the hydraulic cylinder.

[0006] Therefore, a plunger hydraulic cylinder with adjustable stroke buffering is proposed. Summary of the Invention

[0007] The purpose of the present invention is to provide a plunger hydraulic cylinder with adjustable stroke buffering. In order to solve the problem of excessive buffering caused by too large a buffering force when the pressure is relatively large, the length of the plunger is increased by setting an adjusting component to increase the buffering time, thereby improving the buffering effect, and replacing the large buffering force with a short buffering time with a small buffering force and a long buffering time, so as to avoid the problem of excessive buffering force.

[0008] To achieve the above purpose, the present invention provides the following technical solutions:

[0009] An adjustable-stroke buffer plunger hydraulic cylinder, comprising a cylinder block and a sealing pipe, further comprising a push rod, a piston, an adjusting assembly, a plunger assembly and a fixing assembly. The push rod is connected inside the sealing pipe, the piston is connected to the lower end of the push rod. Oil discharge grooves are provided on both the upper and lower sides of the inner wall of the cylinder block. Throttle grooves are provided on both sides of the oil discharge grooves. An adjusting block is connected inside the throttle grooves. An oil outlet is provided on the front side of the outer wall of the cylinder block. The plunger assembly is connected inside the oil discharge groove. The plunger assembly includes a lower plunger, a second spring and an upper plunger. The lower plunger is movably connected inside the oil discharge groove. The second spring is connected to the top of the lower plunger. The upper plunger is sleeved on the outer wall of the lower plunger. The adjusting assembly is connected to the bottom of the oil discharge groove and is connected to the lower plunger. The upper plunger and the lower plunger are fixed by the fixing assembly. When the piston moves downward, it pushes the upper plunger and the lower plunger into the oil discharge groove. When the lower plunger moves to the bottom of the oil discharge groove, the fixing assembly releases the fixation. When the piston moves upward, the adjusting assembly pushes the upper plunger out of the oil discharge groove and adjusts the length of the upper plunger extended by the second spring.

[0010] In the above solution, the length of the plunger assembly is changed by the adjusting assembly to change the length of the buffer stroke, thereby changing the buffer effect. In the prior art, the plunger and the piston are connected together. If the plunger needs to be adjusted, the adjusting structure needs to be placed inside the push rod, but this will affect the strength of the push rod. Therefore, the original plunger is separated and arranged inside the oil discharge groove. At the same time, the adjusting assembly is arranged at the bottom of the oil discharge groove. The upper plunger is pushed to move by the second spring rod, increasing the distance between the upper plunger and the lower plunger, so as to realize the increase of the length of the plunger. And the adjusting assembly is used to change the extension length of the second spring to change the length of the plunger assembly extending out of the oil discharge groove, so as to change the contact time between the piston and the plunger, thereby changing the buffer time of the piston, and further changing the buffer effect of the piston. When pressing down, the distance between the upper plunger and the lower plunger returns to its original state, thus avoiding the shortening of the piston stroke caused by the too long plunger. And when the plunger assembly ends the stroke, the adjusting assembly also plays a buffering role to compensate for the buffering force formed by the narrowed throttle groove.

[0011] Preferably, the adjusting assembly includes an installation cavity, a worm, a worm gear, a connecting shaft, a steel wire, a fixing column and a first spring. The installation cavity is opened below the oil discharge groove. The worm is connected inside the installation cavity and its left end extends to the outer wall of the cylinder block. The worm gear is arranged inside the installation cavity and meshes with the worm. The connecting shaft passes through the middle of the worm gear and is connected to the inside of the installation cavity. The fixing column is connected to the bottom of the oil discharge groove. The first spring is connected to the top of the fixing column. The plunger assembly is connected to the outer wall of the fixing column. The steel wire is connected to the outer wall of the connecting shaft and its upper end passes through the inside of the fixing column and is connected to the upper plunger.

[0012] Since the length of the buffer stroke is determined by the lengths of the oil outlet groove and the plunger assembly, when the length of the plunger assembly is less than or equal to the length of the oil outlet groove, the buffer stroke is equal to the length of the plunger assembly; when the length of the oil outlet groove is less than the length of the plunger assembly, the length of the buffer stroke is equal to the length of the oil outlet groove. Therefore, simply increasing the length of the plunger assembly cannot effectively increase the buffer stroke. In the above solution, by rotating the worm to drive the worm wheel to rotate, when the worm wheel rotates, it drives the connecting shaft to rotate, and the steel wire is wound by the rotation of the connecting shaft to change the extended length of the steel wire, so as to change the extended length of the plunger assembly. When the buffering is over, the whole adjusting assembly will be squeezed back to the original length, thus avoiding the plunger being too long and shortening the stroke of the piston.

[0013] Preferably, the lower plunger is sleeved on the outer wall of the fixed column, and the top of the inner wall is connected to the first spring, and the elastic modulus of the first spring is greater than that of the second spring.

[0014] In the above solution, the elastic modulus of the first spring is greater than that of the second spring, so when the second spring is stretched by the steel wire, the influence on the elongation of the first spring is reduced, so that the first spring can completely push the lower plunger out of the oil outlet groove.

[0015] Preferably, the cross-section of the lower plunger is funnel-shaped with the narrow end facing downwards, and the maximum diameter of the lower plunger is the same as that of the oil outlet groove.

[0016] In the above solution, the cross-section of the lower plunger is trapezoidal. When the lower plunger moves downwards, the distance between the lower plunger and the inner wall of the oil outlet groove gradually decreases. The magnitude of the buffering force received by the piston is determined by the pressure when the hydraulic oil enters the inside of the oil outlet groove. The smaller the opening of the oil outlet groove, the greater the pressure and the greater the buffering force. When the opening of the oil outlet groove gradually decreases, the buffering force received by the piston will also gradually increase, improving the buffering smoothness and avoiding the sudden change of the buffering force received by the piston and causing vibration.

[0017] Preferably, the fixing assembly includes a moving groove, a toothed plate, a clamping block, a return spring and a hollow tube. The moving groove is opened on the left and right sides of the outer wall of the lower plunger. The toothed plate is connected in the moving groove. The clamping blocks are connected to the left and right sides of the inner wall of the upper plunger and cooperate with the toothed plate. The two ends of the return spring are respectively connected to the toothed plate and the inner wall of the moving groove. The hollow tube is connected to the inner wall of the moving groove.

[0018] In the above solution, when pressing downwards, the piston pushes the upper plunger and the lower plunger to move downwards together. When the lower plunger moves to the bottom, the upper plunger begins to move downwards alone, thus avoiding the situation that only the upper plunger moves downwards during the downward movement, so that the extended part of the upper plunger cannot achieve the buffering effect.

[0019] Preferably, the fixing assembly further includes a push rod, a tapered rod and a through hole. A plurality of the through holes are formed in the bottom of the lower plunger. The push rod and the tapered rod are connected to the bottom of the oil outlet groove. The push rod and the tapered rod pass through the through hole and extend into the moving groove. One side of the toothed plate close to the block is provided as an inclined surface and is matched with the push rod. The width of the tapered rod is greater than the inner diameter of the hollow tube.

[0020] In the above solution, when the plunger assembly moves to the bottom, the toothed plate is pushed by the push rod to move, so as to release the fixation between the upper plunger and the lower plunger. Since the second spring is in a stretched state at this time, the lower plunger assembly is fixed by the tapered push rod at the same time to prevent the lower plunger from moving upward. When the upper plunger moves to the bottom, the hollow tube will squeeze the tapered rod to release the fixation of the lower plunger, preparing for the next process.

[0021] Preferably, a storage mechanism is connected to the bottom of the piston. The storage mechanism includes a storage groove, a communication groove, a limiting block, a pressing ring, a ring groove and a third spring. The storage groove is formed in the bottom of the piston. The ring groove is formed in the bottom of the piston. The pressing ring is slidably connected to the inside of the ring groove. The inner wall of the pressing ring is an inclined surface and the width gradually increases from bottom to top. The third spring is connected above the pressing ring. The communication groove is formed on the left and right sides of the storage groove and communicates with the ring groove. The limiting block is slidably connected to the inside of the storage groove. The cross section of the limiting block is a right trapezoid.

[0022] In the above solution, when the piston moves to the bottom, the pressing ring will be pressed into the piston. At this time, the upper plunger moves upward under the action of the first spring and enters the inside of the storage groove, opening the outlet of the oil outlet groove. In the prior art, when the piston starts to extend, since the plunger blocks the outlet of the oil outlet groove, the hydraulic oil can only flow out from the throttling groove, and the moving speed of the piston is determined by the inflow and thrust of the hydraulic oil. The plunger assembly is pushed into the storage groove to increase the oil outlet when starting, and improve the moving speed of the piston when starting.

[0023] Preferably, the upper and lower ends of the communication groove communicate with the storage groove and the inner cavity of the cylinder respectively, and the center line of the communication groove is collinear with the center line of the throttling groove.

[0024] In the above solution, when the upper plunger enters the storage groove, the oil is squeezed into the throttling groove. There is a large resistance when the oil flows out from the storage groove, so as to play a buffering role.

[0025] Preferably, the cross section of the storage groove is an isosceles trapezoid with the narrow end facing down, and the opening diameter at the bottom end of the storage groove is equal to the diameter of the upper plunger.

[0026] In the above solution, since the area of the top of the inner wall of the storage tank is larger than the area of the opening of the storage tank, at this time, the area of the oil thrust on the piston is the sum of the area of the top of the inner wall of the storage tank and the area of the bottom of the piston, minus the opening area, which is larger than the original area of the bottom of the piston. Since the magnitude of the thrust on the piston is related to the area of the piston, the contact surface with the oil is increased, and the thrust is increased.

[0027] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0028] 1. By providing a plunger assembly, the length of the plunger assembly is changed by using an adjusting assembly to change the length of the buffering stroke, and then the buffering effect is changed. Moreover, the cross-section of the lower plunger is set to be funnel-shaped. When the lower plunger moves downward, the distance between the lower plunger and the inner wall of the oil outlet groove gradually decreases, so that the opening of the oil outlet groove gradually decreases, and the buffering force on the piston will also gradually increase, improving the buffering smoothness and avoiding the vibration caused by the sudden change of the buffering force on the piston.

[0029] 2. By providing an adjusting assembly, in addition to adjusting the length of the plunger assembly, when the plunger assembly is compressed, the first spring in the adjusting assembly also plays a buffering role. On the other hand, at the end of the buffering stroke, the first spring provides power for the plunger assembly to enter the storage tank.

[0030] 3. By providing a storage assembly, at the end of buffering, the upper plunger and the lower plunger are pushed into the storage tank, so that when the piston moves upward, the opening of the oil outlet groove is completely opened, increasing the thrust during upward movement, improving the instantaneous speed of the piston during upward movement, and setting the cross-section of the storage tank as an isosceles trapezoid, increasing the area of the piston receiving the hydraulic oil thrust, thereby increasing the thrust of the hydraulic oil on the piston, and further increasing the power of the piston. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is a schematic diagram of the overall structure of the present invention;

[0032] Figure 2 is a schematic side sectional view of the present invention;

[0033] Figure 3 is a schematic front sectional view of the present invention;

[0034] Figure 4 is a schematic diagram of the structure of the plunger assembly of the present invention;

[0035] Figure 5 of the present invention Figure 4 is an enlarged schematic diagram of part B;

[0036] Figure 6 of the present invention Figure 2 is an enlarged schematic diagram of part A;

[0037] Figure 7 Schematic diagram of the plunger assembly of the present invention when not compressed

[0038] Figure 8 Schematic diagram of the plunger assembly of the present invention when compressed

[0039] Figure 9 Schematic diagram of the plunger assembly of the present invention when entering the storage groove

[0040] In the figure: 1, cylinder block; 101, oil outlet groove; 102, throttle groove; 103, adjusting block; 104, oil outlet; 2, sealing tube; 3, push rod; 4, piston; 5, adjusting assembly; 501, installation cavity; 502, worm; 503, worm gear; 504, connecting shaft; 505, steel wire; 506, fixed column; 507, first spring; 6, plunger assembly; 601, lower plunger; 602, second spring; 603, upper plunger; 7, fixing assembly; 701, moving groove; 702, toothed plate; 703, clamping block; 704, return spring; 705, hollow tube; 706, ejector rod; 707, tapered rod; 708, through hole; 8, storage mechanism; 801, storage groove; 802, communication groove; 803, limiting block; 804, pressing ring; 805, annular groove; 806, third spring. Detailed implementation manners

[0041] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention, and combined with the working state to make its structural features more detailed. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0042] Please refer to Figures 1 to 9 , the present invention provides a plunger hydraulic cylinder with adjustable stroke buffer, and the technical solution is as follows:

[0043] A plunger hydraulic cylinder with adjustable stroke buffer, referring to Figure 1 , Figure 2 , Figure 3 , Figure 7 , Figure 8 and Figure 9, including a cylinder block 1 and a sealing pipe 2, further comprising a push rod 3, a piston 4, an adjusting assembly 5, and a plunger assembly 6. The push rod 3 is connected inside the sealing pipe 2, the piston 4 is connected to the lower end of the push rod 3. Oil outlet grooves 101 are formed on the upper and lower sides of the inner wall of the cylinder block 1, throttle grooves 102 are formed on both sides of the oil outlet grooves 101, the throttle grooves 102 communicate with the cylinder block 1, an adjusting block 103 is connected inside the throttle grooves 102, an oil outlet 104 is formed on the front side of the outer wall of the cylinder block 1, and the oil outlet 104 communicates with the oil outlet grooves 101. The plunger assembly 6 is connected inside the oil outlet grooves 101. The plunger assembly 6 includes a lower plunger 601, a second spring 602, and an upper plunger 603. The lower plunger 601 is movably connected inside the oil outlet grooves 101, the second spring 602 is connected to the top of the lower plunger 601, the upper plunger 603 is sleeved on the outer wall of the lower plunger 601, and the inner wall is connected to the second spring 602. The original plunger assembly 6 is split into the upper plunger 603 and the lower plunger 601 and connected by the second spring 602. The second spring 602 pushes the upper plunger 603 to move, increasing the distance between the upper plunger 603 and the lower plunger 601, thereby realizing an increase in the length of the plunger. The adjusting assembly 5 is connected to the bottom of the oil outlet grooves 101 and is connected to the lower plunger 601;

[0044] The upper plunger 603 and the lower plunger 601 are fixed by a fixing assembly 7. When the piston 4 moves downward, it pushes the upper plunger 603 and the lower plunger 601 into the oil outlet grooves 101. When the lower plunger 601 moves to the bottom of the oil outlet grooves 101, the fixing assembly 7 releases the fixation. When the piston 4 moves upward, the adjusting assembly 5 pushes the upper plunger 603 out of the oil outlet grooves 101 and adjusts the extended length of the upper plunger 603 pushed by the second spring 602. At the end of the buffering stroke, the distance between the upper plunger 603 and the lower plunger 601 returns to its original state, thus avoiding the shortening of the stroke of the piston 4 due to the excessive length of the plunger. When adjusting in the face of a larger pressure situation, the adjustment amplitude of the opening of the original throttle grooves 102 is reduced. By changing the extended length of the upper plunger 603 relative to the lower plunger 601 through the adjusting assembly 5, the contact time between the piston 4 and the plunger is changed, thereby changing the buffering time of the piston 4, and further changing the buffering effect of the piston 4. And during the compression process of the plunger assembly, the adjusting assembly 5 also plays a buffering role on the piston 4, compensating for the buffering force formed by the narrowed throttle grooves 102.

[0045] As an implementation manner of the present invention, referring to Figure 4 and Figure 5, the adjusting assembly 5 includes an installation cavity 501, a worm 502, a worm gear 503, a connecting shaft 504, a steel wire 505, a fixing column 506 and a first spring 507. The installation cavity 501 is opened below the oil outlet groove 101. The worm 502 is connected inside the installation cavity 501, and its left end extends to the outer wall of the cylinder block 1. The worm gear 503 is arranged inside the installation cavity 501 and meshes with the worm 502. By rotating the worm 502 to drive the worm gear 503 to rotate, when the worm gear 503 rotates, it drives the connecting shaft 504 to rotate. The connecting shaft 504 passes through the middle of the worm gear 503 and is connected to the inside of the installation cavity 501. The fixing column 506 is connected to the bottom of the oil outlet groove 101. The first spring 507 is connected to the top of the fixing column 506. The plunger assembly 6 is ejected from the oil outlet groove 101 by the first spring 507. The plunger assembly 6 is connected to the outer wall of the fixing column 506. The steel wire 505 is connected to the outer wall of the connecting shaft 504, and its upper end passes through the inside of the fixing column 506 and is connected to the upper plunger 603. By rotating the connecting shaft 504 to wind the steel wire 505, the extending length of the steel wire 505 is changed, so as to change the extending length of the plunger assembly 6.

[0046] As an embodiment of the present invention, refer to Figure 4 and Figure 5 , the lower plunger 601 is sleeved on the outer wall of the fixing column 506, and the top of its inner wall is connected to the first spring 507. The elastic modulus of the first spring 507 is greater than that of the second spring 602. When the second spring 602 is compressed by the adjusting assembly 5, the influence on the elongation of the first spring 507 is reduced, and the first spring 507 can still push the lower plunger 601 out of the oil outlet groove 101.

[0047] As an embodiment of the present invention, refer to Figure 4 and Figure 5 , the cross-section of the lower plunger 601 is set to be funnel-shaped with the narrow end facing downwards. The maximum diameter of the lower plunger 601 is the same as that of the oil outlet groove 101. When the lower plunger 601 moves downwards, the distance between the lower plunger 601 and the inner wall of the oil outlet groove 101 gradually decreases. The magnitude of the buffering force received by the piston 4 is determined by the pressure when the hydraulic oil enters the inside of the oil outlet groove 101. The smaller the opening of the oil outlet groove 101, the greater the pressure and the greater the buffering force. When the opening of the oil outlet groove 101 gradually decreases, the buffering force received by the piston 4 will also gradually increase, improving the buffering smoothness and avoiding vibration caused by sudden changes in the buffering force received by the piston 4.

[0048] As an embodiment of the present invention, refer to Figure 4 and Figure 5, the fixing component 7 includes a moving groove 701, a toothed plate 702, a clamping block 703, a return spring 704 and a hollow tube 705. The moving groove 701 is formed on the left and right sides of the outer wall of the lower plunger 601. The toothed plate 702 is connected in the moving groove 701. The clamping block 703 is connected to the left and right sides of the inner wall of the upper plunger 603 and cooperates with the toothed plate 702. The teeth on the clamping block 703 and the toothed plate 702 are both right-angled triangles. The hypotenuse of the clamping block 703 faces upward, and the hypotenuse of the teeth on the toothed plate 702 faces downward. Therefore, when the upper plunger 603 moves upward, the clamping block 703 will push the toothed plate 702 to move toward the inner wall of the moving groove 701. The two ends of the return spring 704 are respectively connected to the toothed plate 702 and the inner wall of the moving groove 701. When the upper plunger 603 stops moving, the return spring 704 pushes the toothed plate 702 to reset. When the piston 4 presses down the upper plunger 603, the plane of the clamping block 703 fits with the plane of the teeth on the toothed plate 702, so as to realize the fixation of the upper plunger 603 and the lower plunger 601 in the vertical direction. At this time, the clamping block 703 drives the lower plunger 601 to move downward together by pushing the toothed plate 702 downward, thus avoiding the situation that only the upper plunger 603 moves downward during the downward movement, so that the extended part between the upper plunger 603 and the lower plunger 601 cannot achieve the buffering effect. The hollow tube 705 is connected to the inner wall of the moving groove 701.

[0049] As an implementation manner of the present invention, refer to Figure 4 and Figure 5, the fixing component 7 further includes a push rod 706, a tapered rod 707 and a through hole 708. A plurality of the through holes 708 are formed at the bottom of the lower plunger 601. The push rod 706 and the tapered rod 707 are connected to the bottom of the oil outlet groove 101. The push rod 706 and the tapered rod 707 pass through the through hole 708 and extend into the moving groove 701. The tapered rod 707 is made of an elastic material. One side of the toothed plate 702 close to the latch 703 is set as an inclined surface and is matched with the push rod 706. The width of the tapered rod 707 is greater than the inner diameter of the hollow tube 705. When the plunger assembly 6 moves to the bottom, the toothed plate 702 is pushed to move by the push rod 706, so as to release the fixation between the upper plunger 603 and the lower plunger 601, so that the lower plunger 601 will not be interfered by the toothed plate 702 when moving downward. The width of the tapered rod 707 is greater than the length of the diameter of the through hole 708 and the length of the inner diameter of the hollow tube 705. Since the second spring 602 is in a stretched state during the downward pressing process, when the fixation between the upper plunger 603 and the lower plunger 601 is in contact, the lower plunger 601 moves upward under the pulling force of the second spring 602 and the pushing force of the first spring 507, and will generate an impact with the downward moving upper plunger 603. The tapered push rod 3 passes through the through hole 708 to fix the lower plunger 601 and prevent the lower plunger 601 from moving upward. When the upper plunger 603 moves to the bottom, it will push the hollow tube 705 to squeeze the tapered rod 707 and make the tapered rod 707 enter the hollow tube 705, thereby releasing the fixation of the lower plunger 601 and preparing for the next process.

[0050] As an implementation manner of the present invention, refer to Figure 4 , Figure 5 and Figure 6, a storage mechanism 8 is connected to the bottom of the piston 4. The storage mechanism 8 includes a storage groove 801, a communication groove 802, a limit block 803, a pressure ring 804, a ring groove 805, and a third spring 806. The storage groove 801 is formed at the bottom of the piston 4. The ring groove 805 is formed at the bottom of the piston 4. The pressure ring 804 is slidably connected to the inside of the ring groove 805. The inner wall of the pressure ring 804 is inclined, and the width gradually increases from bottom to top. The third spring 806 is connected above the pressure ring 804. The communication groove 802 is formed on the left and right sides of the storage groove 801 and communicates with the ring groove 805. The limit block 803 is slidably connected to the inside of the storage groove 801. The cross-section of the limit block 803 is a right trapezoid. Initially, the right-angled side of the limit block 803 contacts the flat surface of the pressure ring 804, restricting the movement of the limit block 803 into the communication groove 802. By the limit block 803, the upper plunger 603 is pushed downward. When the piston 4 moves to the bottom, the pressure ring 804 is squeezed into the ring groove 805, releasing the fixation of the limit block 803. At this time, the upper plunger 603 and the lower plunger 601 move upward under the action of the spring, pushing the limit block 803 into the communication groove 802 and then into the inside of the storage groove 801, opening the outlet of the oil outlet groove 101 to increase the oil output during opening and improving the moving speed of the piston 4 during startup.

[0051] As an embodiment of the present invention, referring to Figure 4 , Figure 5 and Figure 6 , the upper and lower ends of the communication groove 802 communicate with the storage groove 801 and the inner cavity of the cylinder block 1 respectively. The center line of the communication groove 802 is collinear with the center line of the throttle groove 102. When the upper plunger 603 enters the storage groove 801, the oil is squeezed into the throttle groove 102. There is a large resistance when the oil flows out from the storage groove 801, thus playing a buffering role.

[0052] As an embodiment of the present invention, referring to Figure 4 and Figure 5 and Figure 6 , the cross-section of the storage groove 801 is an isosceles trapezoid with the narrow end facing down. The opening diameter at the bottom end of the storage groove 801 is equal to the diameter of the upper plunger 603. Since the area of the inner wall top of the storage groove 801 is larger than the area of the opening, the thrust area of the oil on the piston 4 at this time is the sum of the area of the inner wall top of the storage groove 801 and the area of the bottom of the piston 4, minus the opening area, which is larger than the original area of the bottom of the piston 4. Since the magnitude of the thrust on the piston 4 is related to the area of the piston 4, the contact surface with the oil is increased, and the thrust is improved.

[0053] Working principle: When the push rod 3 extends, the hydraulic oil enters the inside of the cylinder block 1 from the lower oil outlet 104, pushing the piston 4 to move upward to achieve extension. When the push rod 3 shortens, the hydraulic oil enters the inside of the cylinder block 1 from the upper oil outlet 104, pushing the piston 4 to move downward, causing the push rod 3 to contract into the inside of the cylinder block 1 to achieve contraction.

[0054] In order to avoid the phenomenon of excessive buffering caused by excessive buffering force during contraction, the length of the plunger assembly 6 is adjusted through the adjusting assembly 5 to change the buffering duration of the piston 4 and thus change the buffering effect.

[0055] Specifically, by rotating the worm 502, the steel wire 505 is wound around the connecting shaft 504, thereby restricting the extension length of the upper plunger 603. When the piston 4 moves downward, buffering starts when the limit block 803 at the bottom of the piston 4 contacts the upper plunger 603. The limit block 803 first pushes the upper plunger 603 downward, and when the upper plunger 603 moves downward, it drives the lower plunger 601 downward. When the lower plunger 601 moves to the bottom, the lower plunger 601 is fixed by the tapered rod 707. The ejector rod 706 pushes the toothed plate 702 to release the fixation between the upper plunger 603 and the lower plunger 601, and the lower plunger 601 continues to move downward. When the lower plunger 601 completely enters the oil outlet groove 101, the buffering is completed.

[0056] When the piston 4 moves to the lowest position, the piston 4 pushes the hollow tube 705 downward through the upper plunger 603. When the hollow tube 705 moves downward, it squeezes the outer wall of the tapered rod 707 and causes the tapered rod 707 to enter the inside of the hollow tube 705, thereby releasing the fixation of the tapered rod 707 on the lower plunger 601. At the same time, the pressure ring 804 enters the ring groove 805 to release the fixation of the limit block 803. At this time, under the push of the first spring 507, the upper plunger 603 and the lower plunger 601 push the limit block 803 into the ring groove 805, and then the upper plunger 603 and the lower plunger 601 enter the inside of the storage groove 801.

[0057] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principle and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A plunger hydraulic cylinder with adjustable stroke buffer, comprising a cylinder body (1) and a sealing tube (2), characterized in that: The invention also comprises a push rod (3), a piston (4), an adjusting assembly (5), a plunger assembly (6) and a fixing assembly (7); the push rod (3) is connected to the inside of the sealing tube (2); the piston (4) is connected to the lower end of the push rod (3); the inner wall of the cylinder body (1) is provided with oil outlet grooves (101) on the upper and lower sides; the oil outlet groove (101) is provided with throttling grooves (102) on both sides; the throttling groove (102) is connected to the inside of the adjusting block (103); the outer wall of the cylinder body (1) is provided with an oil outlet (104) on the front side; the plunger assembly (6) is connected to the inside of the oil outlet groove (101); the plunger assembly (6) comprises a lower plunger (601), a second spring (602) and an upper plunger (603); the lower plunger (601) is movably connected to the inside of the oil outlet groove (101); The second spring (602) is connected to the top of the lower plunger (601), the upper plunger (603) is sleeved on the outer wall of the lower plunger (601), the adjusting component (5) is connected to the bottom of the oil outlet groove (101) and is connected to the lower plunger (601), the upper plunger (603) and the lower plunger (601) are fixed by a fixing component (7), when the piston (4) moves downward, the upper plunger (603) and the lower plunger (601) are pushed into the oil outlet groove (101), when the lower plunger (601) moves to the bottom of the oil outlet groove (101), the fixing component (7) is released, when the piston (4) moves upward, the adjusting component (5) pushes the upper plunger (603) out of the oil outlet groove (101), and adjusts the length of the upper plunger (603) pushed and extended by the second spring (602).

2. The plunger hydraulic cylinder with adjustable stroke buffer according to claim 1, characterized in that: The adjusting assembly (5) comprises an installation cavity (501), a worm (502), a worm wheel (503), a connecting shaft (504), a steel wire (505), a fixing column (506) and a first spring (507). The installation cavity (501) is opened below the oil outlet groove (101). The worm (502) is connected to the inside of the installation cavity (501), and the left end of the worm (502) extends to the outer wall of the cylinder body (1). The worm wheel (503) is arranged in the inside of the installation cavity (501) and is connected to the worm (502). 2) meshing, the connecting shaft (504) passes through the middle of the worm gear (503) and is connected to the inside of the installation cavity (501), the fixing column (506) is connected to the bottom of the oil outlet groove (101), the first spring (507) is connected to the top of the fixing column (506), the plunger assembly (6) is connected to the outer wall of the fixing column (506), the steel wire (505) is connected to the outer wall of the connecting shaft (504), and the upper end passes through the inside of the fixing column (506) and is connected to the upper plunger (603).

3. The plunger hydraulic cylinder with adjustable stroke buffer according to claim 2, characterized in that: The lower plunger (601) is sleeved on the outer wall of the fixed column (506), and the top of the inner wall is connected to the first spring (507), and the elastic modulus of the first spring (507) is greater than the elastic modulus of the second spring (602).

4. The plunger hydraulic cylinder with adjustable stroke buffer according to claim 3, characterized in that: The cross section of the lower plunger (601) is funnel-shaped, with the narrow end facing downwards, and the maximum diameter of the lower plunger (601) is the same as that of the oil outlet groove (101).

5. The plunger hydraulic cylinder with adjustable stroke buffer according to claim 3, characterized in that: The fixing assembly (7) comprises a movable groove (701), a tooth plate (702), a block (703), a return spring (704) and a hollow tube (705); the movable groove (701) is provided on the left and right sides of the outer wall of the lower plunger (601); the tooth plate (702) is connected to the movable groove (701); the block (703) is connected to the left and right sides of the inner wall of the upper plunger (603) and cooperates with the tooth plate (702); two ends of the return spring (704) are respectively connected to the tooth plate (702) and the inner wall of the movable groove (701); and the hollow tube (705) is connected to the inner wall of the movable groove (701).

6. The plunger hydraulic cylinder with adjustable stroke buffer according to claim 5, characterized in that: The fixing assembly (7) further comprises a push rod (706), a tapered rod (707) and a through hole (708); a plurality of the through holes (708) are provided at the bottom of the lower plunger (601); the push rod (706) and the tapered rod (707) are connected to the bottom of the oil outlet groove (101); the push rod (706) and the tapered rod (707) extend through the through hole (708) to the inside of the movable groove (701); a side of the tooth plate (702) close to the block (703) is provided as an inclined surface and cooperates with the push rod (706); and the width of the tapered rod (707) is greater than the inner diameter of the hollow tube (705).

7. The plunger hydraulic cylinder with adjustable stroke buffer according to claim 3, characterized in that: The bottom of the piston (4) is connected to a storage mechanism (8), and the storage mechanism (8) comprises a storage groove (801), a connecting groove (802), a stopper (803), a pressure ring (804), an annular groove (805) and a third spring (806). The storage groove (801) is provided at the bottom of the piston (4), the annular groove (805) is provided at the bottom of the piston (4), the pressure ring (804) is slidably connected to the inside of the annular groove (805), the inner wall of the pressure ring (804) is an inclined surface, and the width gradually increases from bottom to top, the third spring (806) is connected to the top of the pressure ring (804), the connecting groove (802) is provided at the left and right sides of the storage groove (801), and is connected to the annular groove (805), the stopper (803) is slidably connected to the inside of the storage groove (801), and the cross section of the stopper (803) is set to be a right-angled trapezoid.

8. The plunger hydraulic cylinder with adjustable stroke buffer according to claim 7, characterized in that: The upper and lower ends of the connecting groove (802) are respectively connected to the storage groove (801) and the inner cavity of the cylinder body (1), and the center line of the connecting groove (802) is colinear with the center line of the throttling groove (102).

9. The plunger hydraulic cylinder with adjustable stroke buffer according to claim 7, characterized in that: The cross section of the storage groove (801) is set to be an isosceles trapezoid with the narrow end facing downward, and the opening diameter of the bottom end of the storage groove (801) is equal to the diameter of the upper plunger (603).

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