Multi-stage lifting oil cylinder

Abstract

The utility model discloses a multi-stage lifting oil cylinder which comprises an outer cylinder and a piston rod arranged in the center of the outer cylinder, a plurality of stages of telescopic sleeves are arranged between the outer cylinder and the piston rod, the sleeves are integrally of an equal-wall-thickness structure, and a plurality of sealing grooves for fixing guide sealing pieces are formed in the inner walls of the front ends of the sleeves. An inner limiting groove for fixing the inner limiting ring is formed in the inner wall of the front portion of the sleeve on the rear side of the sealing groove, an outer limiting groove for fixing the outer limiting ring is formed in the outer wall of the rear portion of the sleeve, and a check ring groove for fixing the check ring is further formed in the inner wall of the rear end of the sleeve. The sleeve adopts an integrated equal-wall-thickness structure, the structure is simple and compact, the processing technology is simplified, the cost is reduced, and the safety and the reliability of the multistage lifting oil cylinder are improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of hydraulic oil cylinders, in particular to a multi-stage lifting oil cylinder. Background Art

[0002] The multi-stage lifting cylinders of dump trucks in the prior art are basically similar in structure. Figure 4 As shown, a piston rod 3 is arranged in the center of an outer cylinder 2 with a closed rear end, and a sleeve 15 and a sleeve 2 16 are arranged between the outer cylinder 2 and the piston rod 3. The outer walls of the sleeves 15 and 16 at the rear end are integrally provided with a step 21 protruding outward, and a groove is formed between adjacent steps 21 for setting a support ring 12; in addition, a guide sleeve 20 for installing a guide seal 4 is welded to the front end of the sleeves 15 and 16, and the guide sleeve 20 also has a step protruding inward relative to the sleeve as an inner limit structure. In order to ensure that the multi-stage cylinder can be extended in sequence, steps need to be set at each level of the sleeve structure to play a limit role, so the sleeve is often welded by two sections of material. This structure is complicated to process, and two sections of material need to be processed first, and then welded. There is a large waste of materials, high cost, and no price advantage. There is a step protruding outward on the outer circle of the sleeve, which can only be processed by an external cylindrical grinder, and the processing efficiency is low. There is also a step hole on the inner hole of the sleeve, and the inner hole can only be rolled and formed before welding, so there are problems such as welding deformation. Therefore, this type of multi-stage lifting cylinder in the prior art has defects such as welding deformation and large processing errors. The straightness of the inner and outer circles of each stage of the cylinder is difficult to ensure, resulting in uneven friction between the sleeves of each stage when the multi-stage cylinder is extended and retracted, and disorder will occur when the multi-stage cylinder is extended. When the disorder is serious, the impact force on the car body is increased, and safety accidents may occur. Utility Model Content

[0003] The purpose of the utility model is to solve the above problems existing in the multi-stage lifting cylinder of the prior art and to provide a multi-stage lifting cylinder which has the advantages of convenient processing, low cost and high safety.

[0004] The technical solution adopted by the utility model to solve the above-mentioned technical problems is a multi-stage lifting cylinder, including an outer cylinder with a closed rear end and an oil port and a piston rod arranged at the center of the outer cylinder, a plurality of stages of retractable sleeves are arranged between the outer cylinder and the piston rod, the sleeve as a whole is a uniform wall thickness structure, a plurality of sealing grooves for fixing the guide seal are arranged on the inner wall of the front end of the sleeve, an inner limit groove for fixing the inner limit ring is arranged on the inner wall of the front part of the sleeve on the rear side of the sealing groove, an outer limit groove for fixing the outer limit ring is arranged on the outer wall of the rear part of the sleeve, and a retaining ring groove for fixing the retaining ring is also arranged on the inner wall of the rear end of the sleeve. The multi-stage sleeves of the utility model all adopt a structure of equal wall thickness, and no raised step-shaped structures are arranged on the inner wall and the outer wall of the sleeve, wherein the inner limit structure located on the inner wall of the sleeve is obtained by machining an inner limit groove on the inner wall of the sleeve and arranging an inner limit ring in the inner limit groove; the guide seal located on the front end of the inner wall of the sleeve is installed in the sealing groove on the inner wall of the sleeve; the outer limit structure located on the outer wall of the sleeve is obtained by machining an outer limit groove on the outer wall of the sleeve and arranging an outer limit ring in the outer limit groove; the supporting ring located on the outer wall of the sleeve is positioned by two outer limit rings on the outer wall of the sleeve. In this way, there is no step-like structure protruding from the reference cylinder wall on the inner wall and the outer wall of the sleeve. The sleeve of the utility model can be obtained by one-time processing of the pipe without welding. Not only is the processing convenient and low-cost, but the sleeve will not be deformed due to welding. It effectively solves the defects of welding deformation and large processing errors in the multi-stage lifting cylinder in the prior art, and it is difficult to ensure the straightness of the inner and outer circles of each stage of the cylinder, resulting in uneven friction between the sleeves at each stage when the multi-stage cylinder is extended and retracted, and disorder will occur when the multi-stage cylinder is extended. When the disorder is serious, it will increase the impact force on the car body and cause safety accidents.

[0005] Preferably, the outer tube is of equal wall thickness structure, and a plurality of sealing grooves for fixing the guide seal are provided on the inner wall of the front part of the outer tube, and an inner limit groove is provided on the inner wall of the outer tube behind the sealing groove, and an inner limit ring is provided in the inner limit groove. The outer tube of the utility model adopts an equal wall thickness structure, and no raised step-like structure is provided on the inner wall of the outer tube, wherein the inner limit structure located on the inner wall of the outer tube is obtained by machining an inner limit groove on the inner wall of the outer tube and providing an inner limit ring in the inner limit groove; the guide seal located at the front end of the inner wall of the outer tube is installed in the sealing groove of the inner wall of the outer tube; in this way, there is no step-like structure protruding from the reference tube wall on the inner wall of the outer tube, and the outer tube can be obtained by one-time processing of pipes, without the need for welding combination, and has the advantages of convenient processing, low cost and high reliability.

[0006] Preferably, a plurality of outer limit grooves are arranged on the outer wall of the rear part of the piston rod, and an outer limit ring is arranged in the outer limit groove. The outer limit ring is used for limiting the position of the piston rod and sleeve of the multi-stage lifting oil cylinder when they are extended and retracted and for positioning the position of the support ring to ensure that the piston rod and sleeve of the multi-stage lifting oil cylinder are extended and retracted in an orderly manner.

[0007] Preferably, there are three outer limit rings, and a support ring is provided between the two outer limit rings at the rear side. The outer limit ring at the front side cooperates with the corresponding inner limit ring to limit the maximum extension position of the sleeve or piston rod; the two outer limit rings at the rear side are used to position the support rings, which are used to prevent the sleeves from scratching each other and generating eccentric loads when moving; the outer limit ring at the rear position also cooperates with the corresponding retaining ring to control the telescopic sequence of the sleeve or piston rod.

[0008] Preferably, the wall of the rear part of the sleeve is provided with a flow hole, the center of the rear end of the piston rod is provided with a cavity, the wall of the cavity is provided with a flow hole, and the flow hole is located between the two outer limit rings on the front side. The flow hole is used to connect the piston rod with the inter-tube cavity between the sleeve and the outer cylinder, so that the hydraulic oil can flow between adjacent inter-tube cavities to promote the extension and contraction of the piston rod and the sleeve.

[0009] Preferably, there are two support rings between the two outer limit rings on the sleeve and the piston rod, and the total width of the two support rings matches the width of the gap between the two outer limit rings. The total width of the two support rings matches the width of the gap between the two outer limit rings to ensure the stability of the support ring position without relative sliding.

[0010] Preferably, the retaining ring groove is located at the rear side of the outer limit groove, the retaining ring groove is semicircular and its front groove wall is provided with an inclined surface, the retaining ring is a steel wire retaining ring, and the depth of the retaining ring groove is less than the steel wire diameter of the steel wire retaining ring. The depth of the retaining ring groove is less than the steel wire diameter of the steel wire retaining ring, so that a part of the steel wire retaining ring protrudes outside the retaining ring groove, so that the retaining ring cooperates with the corresponding outer limit ring to drive the sleeve or piston rod at the adjacent position to move.

[0011] Preferably, there is one inner limit ring, which is arranged near the front guide seal. The inner limit ring is used to limit the maximum extension length of the adjacent sleeve or piston rod. When the outer limit ring located at the front side of the inner layer moves to abut against the inner limit ring of the outer layer, the sleeve or piston rod located at the inner layer cannot be extended further.

[0012] Preferably, the sealing groove comprises a wide groove and narrow grooves located on both sides of the wide groove, and the length of the cylinder wall between two adjacent sealing grooves is the same.

[0013] The beneficial effect of the utility model is that it effectively solves the problems of the prior art that the multi-stage lifting cylinder processing technology is complex, the cost is high and the processing error is large, the multi-stage cylinder is prone to disorder when extending, the impact on the car body is large and may cause safety accidents. The multi-stage lifting cylinder sleeve of the utility model adopts an integrated equal wall thickness structure, the structure is simple and compact, which greatly simplifies the processing technology and reduces material and processing costs; the cylinder is lightweight designed to reduce the weight of the whole machine and save energy; the cylinder is easy to install and the parts are highly versatile, which is convenient for organizing production and assembly to meet the needs of different hosts and customers, while improving the safety and reliability of the multi-stage lifting cylinder. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a structural sectional view of the multi-stage lifting cylinder of the utility model.

[0015] Figure 2 It is a partial structural sectional view of the rear end of the multi-stage lifting cylinder of the utility model.

[0016] Figure 3 It is a partial structural sectional view of the front end of the multi-stage lifting cylinder of the utility model.

[0017] Figure 4 It is a structural sectional view of a multi-stage lifting cylinder in the prior art.

[0018] In the figure: 1. oil port, 2. outer cylinder, 3. piston rod, 4. guide seal, 5. sealing groove, 6. inner limit ring, 7. inner limit groove, 8. outer limit ring, 9. outer limit groove, 10. retaining ring, 11. retaining ring groove, 12. support ring, 13. flow hole, 14. cavity, 15, sleeve one, 16. sleeve two, 17. sleeve three, 18. cylinder bottom, 19. inter-cylinder cavity, 20. guide sleeve, 21. step. DETAILED DESCRIPTION

[0019] The specific implementation of the technical solution of the utility model is further described below through examples and in conjunction with the accompanying drawings.

[0020] Example 1

[0021] In such Figure 1 Figure 2 Figure 3In the embodiment 1 shown, a multi-stage lifting oil cylinder is provided. The front end of the oil cylinder is the extended end of the piston and the sleeve, and the rear end is the fixed support end. The oil cylinder includes an outer cylinder 2. The rear end of the outer cylinder 2 is closed by the cylinder bottom 18. The oil port 1 for entering and exiting the hydraulic oil is arranged on the cylinder bottom 18. The piston rod 3 is arranged at the center of the outer cylinder 2. A multi-stage retractable sleeve is arranged between the outer cylinder 2 and the piston rod 3. In this embodiment, a three-stage retractable sleeve is arranged between the outer cylinder 2 and the piston rod 3. The sleeve is sleeve one 15, the sleeve close to the piston rod 3 is sleeve three 17, and the sleeve between sleeve one 15 and sleeve three 17 is sleeve two 16; gaps are provided between the outer cylinder 2 and sleeve one 15, sleeve one 15 and sleeve two 16, sleeve two 16 and sleeve three 17, and sleeve three 17 and the piston rod 3, and the gaps constitute an inter-cylinder cavity 19, and hydraulic oil can enter the inter-cylinder cavity 19 to ensure smooth extension and retraction of the piston rod 3, sleeve one 15, sleeve two 16, and sleeve three 17. The sleeve 15, the sleeve 2 16 and the sleeve 3 17 are all of equal wall thickness structure as a whole, that is, there is no outward or inward protrusion structure on the reference line of the inner wall and the outer wall of the sleeve 15, the sleeve 2 16 and the sleeve 3 17; the inner wall of the front end of the sleeve 15, the sleeve 2 16 and the sleeve 3 17 is provided with a plurality of sealing grooves 5 for fixing the guide seal 4, the cross section of the sealing groove 5 is rectangular, and the bottom of the sealing groove 5 is concave relative to the reference line of the inner wall of the sleeve; the sealing grooves 5 on the sleeve 15, the sleeve 2 16 and the sleeve 3 17 of this embodiment are all 5, guide seals 4 are arranged in the sealing grooves 5, the outer side of the guide seals 4 is embedded in the sealing grooves 5, and the inner side of the guide seals 4 is tightly sealed with the corresponding sleeves or piston rods 3; wherein the guide seals 4 on the inner wall of the front end of sleeve 15 are used for guide sealing between sleeve 1 15 and sleeve 2 16, the guide seals 4 on the inner wall of the front end of sleeve 2 16 are used for guide sealing between sleeve 2 16 and sleeve 3 17, and the guide seals 4 on the inner wall of the front end of sleeve 3 17 are used for guide sealing between sleeve 3 17 and piston rod 3. The sealing grooves 5 of this embodiment include a wide groove and narrow grooves located on both sides of the wide groove, the length of the barrel wall between two adjacent sealing grooves 5 is the same, and the wide groove and the narrow groove are respectively used to set guide seals 4 with different performances.

[0022] An inner limit groove 7 for fixing an inner limit ring 6 is provided on the front inner walls of sleeve 15, sleeve 2 16 and sleeve 3 17 at the rear side of the sealing groove 5, and the bottom of the inner limit groove 7 is recessed relative to the inner wall reference line of the sleeve; in this embodiment, the inner limit groove 7 on the front inner walls of sleeve 15, sleeve 2 16 and sleeve 3 17 is only one, and its cross-section is rectangular, and the inner limit groove 7 is located on the rear side of the last sealing groove 5 of the five sealing grooves 5 at the front end, that is, the inner limit groove 7 is arranged close to the guide seal 4 at the front end, so that the sleeve has a larger telescopic range; an inner limit ring 6 is provided in the inner limit groove 7, and the cross-section of the inner limit ring 6 is rectangular. An outer limit groove 9 is provided on the outer wall of the rear part of the sleeve, and the cross section of the outer limit groove 9 is rectangular, and the groove bottom of the outer limit groove 9 is concave relative to the outer wall reference line of the sleeve; there are three outer limit grooves 9 on the outer wall of the rear part of sleeve 15, sleeve 2 16 and sleeve 3 17, and an outer limit ring 8 is arranged in the outer limit groove 9, and the cross section of the outer limit ring 8 is rectangular, wherein a support ring 12 is provided between the two outer limit rings 8 located at the rear side, and the support ring 12 is located between the protruding parts of the two outer limit rings 8 at the rear side, and the inner side surface of the support ring 12 is in close contact with the sleeve, and the outer side surface is in close contact with the inner wall of the adjacent sleeve or outer cylinder 2. The outer limit ring 8 is used for limiting and positioning the position of the support ring 12 when the sleeve of the multi-stage lifting cylinder is extended and retracted, so as to ensure that the sleeve of the multi-stage lifting cylinder is extended and retracted in an orderly manner.

[0023] A retaining ring groove 11 for fixing the retaining ring 10 is also provided on the inner wall at the rear end of the sleeve. The retaining ring groove 11 is located on the rear side of an outer limit groove 9 at the rear end. The retaining ring groove 11 is semicircular and its front groove wall is provided with an inclined surface. The retaining ring 10 is a steel wire retaining ring. Usually, the depth of the retaining ring groove 11 is less than the steel wire diameter of the steel wire retaining ring. In this embodiment, the depth of the retaining ring groove 11 is half the steel wire diameter of the steel wire retaining ring.

[0024] The outer cylinder 2 of this embodiment is also of equal wall thickness structure, and there is no outward or inward protrusion structure on the reference line between the inner wall and the outer wall of the outer cylinder 2; a plurality of sealing grooves 5 for fixing the guide seal 4 are provided on the inner wall of the front part of the outer cylinder 2, and the cross section of the sealing groove 5 is rectangular, and the groove bottom of the sealing groove 5 is recessed relative to the inner wall reference line of the outer cylinder 2; there are 5 sealing grooves 5 in this embodiment, and the guide seal 4 is arranged in the sealing groove 5, and the outer side surface of the guide seal 4 is embedded in the sealing groove 5, and the inner side surface of the guide seal 4 is tightly sealed with the sleeve 15; the guide seal 4 on the inner wall of the front end of the outer cylinder 2 is used for guiding sealing between the outer cylinder 2 and the sleeve 15. An inner limit groove 7 is provided on the inner wall of the outer cylinder 2 at the rear side of the sealing groove 5, and the bottom of the inner limit groove 7 is recessed relative to the inner wall reference line of the outer cylinder 2; in this embodiment, there is one inner limit groove 7 on the inner wall of the front part of the outer cylinder 2, and its cross section is rectangular. The inner limit groove 7 is located at the rear side of the last sealing groove 5 among the five sealing grooves 5 at the front end, that is, the inner limit groove 7 is arranged close to the guide seal 4 at the front end, so that the sleeve can have a larger telescopic range; an inner limit ring 6 is provided in the inner limit groove 7, and the cross section of the inner limit ring 6 is rectangular. The outer cylinder 2 of the utility model adopts a uniform wall thickness structure, and no raised step-like structure is arranged on the inner wall of the outer cylinder 2, wherein the inner limit structure located on the inner wall of the outer cylinder 2 is obtained by machining an inner limit groove 7 on the inner wall of the outer cylinder 2 and arranging an inner limit ring 6 in the inner limit groove 7; the guide seal 4 located at the front end of the inner wall of the outer cylinder 2 is installed in the sealing groove 5 on the inner wall of the outer cylinder 2; in this way, there is no step-like structure protruding from the reference cylinder wall on the inner wall of the outer cylinder 2, and the outer cylinder 2 can be obtained by one-time processing of the pipe without the need for welding combination, which has the advantages of convenient processing, low cost and high reliability.

[0025] An outer limit groove 9 is also provided on the outer wall of the rear part of the piston rod 3, and an outer limit ring 8 is provided in the outer limit groove 9. The cross section of the outer limit groove 9 is rectangular, and the groove bottom of the outer limit groove 9 is recessed relative to the outer wall of the piston rod 3; there are three outer limit grooves 9 on the outer wall of the rear part of the piston rod 3, and an outer limit ring 8 is provided in the outer limit groove 9, and the cross section of the outer limit ring 8 is rectangular, wherein a support ring 12 is provided between the two outer limit rings 8 located at the rear side, and the support ring 12 is located between the protruding parts of the two outer limit rings 8 at the rear side, and the inner side surface of the support ring 12 is in close contact with the piston rod 3, and the outer side surface is in close contact with the inner wall of the sleeve three 17. In this embodiment, there are two support rings 12 between the two outer limit rings 8 on the sleeve and the piston rod 3, and the total width of the two support rings 12 is adapted to the width of the gap between the two outer limit rings 8. The support ring 12 is used to prevent the sleeves from scratching each other and generating eccentric loads when moving.

[0026] A through hole 13 is provided on the cylinder wall at the rear of the sleeve 15, and the through hole 13 is located between the two outer limit rings 8 on the front side of the sleeve 15. The through hole 13 connects the outer cylinder 2 with the sleeve 15 and the cylinder cavity 19 between the sleeve 15 and the sleeve 2 16, so that the hydraulic oil can flow smoothly between the outer cylinder 2 and the sleeve 15 and the cylinder cavity 19 between the sleeve 15 and the sleeve 2 16; a through hole 13 is provided on the cylinder wall at the rear of the sleeve 2 16, and the through hole 13 is located between the two outer limit rings 8 on the front side of the sleeve 2 16, and the through hole 13 connects the sleeve 15 with the sleeve 2 16 and the sleeve The inter-tube cavity 19 between sleeve 16 and sleeve three 17 allows the hydraulic oil to flow smoothly between the inter-tube cavity 19 between sleeve 15 and sleeve 2 16 and between sleeve 2 16 and sleeve three 17; a flow hole 13 is provided on the tube wall at the rear of sleeve three 17, and the flow hole 13 is located between the two outer limit rings 8 on the front side of sleeve three 17. The flow hole 13 connects sleeve 2 16 and sleeve three 17 and the inter-tube cavity 19 between sleeve three 17 and piston rod 3, so that the hydraulic oil can flow smoothly between the inter-tube cavity 19 between sleeve 2 16 and sleeve three 17 and between sleeve three 17 and piston rod 3. The front end of the piston rod 3 is a solid structure, and a cavity 14 is provided in the center of the rear end of the piston rod 3. The rear end of the cavity 14 is open and communicates with the oil port 1 on the bottom 18 of the rear end cylinder of the outer tube 2; a flow hole 13 is also provided on the wall of the cavity 14, and the flow hole 13 is located between the two outer limit rings 8 on the front side of the piston rod 3. The flow hole 13 connects the cavity 14 and the inter-tube cavity 19 between the piston rod 3 and the sleeve three 17, so that the hydraulic oil can flow smoothly between the inter-tube cavity 19 between the sleeve three 17 and the piston rod 3 and the cavity 14 at the rear end of the piston rod 3; when the piston rod 3 and the sleeve are both in the retracted position, the above-mentioned flow hole 13 is roughly in the same radial position on the cylinder.

[0027] When assembling the oil cylinder, first install the guide seal 4 and the inner limit ring 6 on the outer tube 2; install the guide seal 4, the inner limit ring 6, the outer limit ring 8 and the supporting ring 12 on the sleeve 15, and push the outer tube 2 from the rear end of the outer tube 2; install the guide seal 4, the inner limit ring 6, the outer limit ring 8 and the supporting ring 12 on the sleeve 2 16, push the sleeve 1 15 from the rear end of the sleeve 1 15, and then install the retaining ring 10 on the inner wall of the rear end of the sleeve 1 15; install the guide seal 4, the inner limit ring 6, the outer limit ring 8 and the supporting ring 12 on the sleeve 3 17, push the sleeve 2 16 from the rear end of the sleeve 2 16, and then install the retaining ring 10 on the inner wall of the rear end of the sleeve 2 16; install the outer limit ring 8 and the supporting ring 12 on the piston rod 3, push the sleeve 3 17 from the rear end of the sleeve 3 17, and then install the retaining ring 10 on the inner wall of the rear end of the sleeve 3 17, and finally install the cylinder bottom 18.

[0028] The working process of the multi-stage lifting cylinder of the utility model is as follows: when the piston rod 3 and the sleeve need to be extended, the oil port 1 is in the oil inlet state, and the hydraulic oil enters the rear end of the cylinder from the oil port 1. Since the cross-sectional areas of the sleeve 15, the second sleeve 16 and the third sleeve 17 are different, the sleeve with a larger area has a larger output thrust. Therefore, the sleeve with a larger area, i.e., the sleeve 15, is first pushed out by the hydraulic oil at the rear end of the cylinder. During the ejection process of the sleeve 15, the hydraulic oil in the inter-tube cavity 19 between the outer tube 2 and the sleeve 15 passes through the sleeve 15, the second sleeve 16, the third sleeve 17 and the flow hole 13 on the piston rod 3 and enters the rear end of the cylinder. On the other hand, since the wire retaining ring on the inner wall of its rear end abuts against the last outer limit ring 8 on the outer wall of the second sleeve 16, the sleeve 15 drives the second sleeve 16 to extend. Similarly, when the second sleeve 16 is extended, the inter-tube cavity 19 between the sleeve 15 and the second sleeve 16 is pushed out. The hydraulic oil in 9 enters the rear end of the cylinder through the sleeve two 16, the sleeve three 17 and the flow hole 13 on the piston rod 3. In addition, since the wire retaining ring on the inner wall of the rear end of the sleeve two 16 abuts with the last outer limit ring 8 on the outer wall of the sleeve three 17, the sleeve two 16 drives the sleeve three 17 to extend. When the sleeve three 17 is extended, the hydraulic oil in the cylinder cavity 19 between the sleeve two 16 and the sleeve three 17 enters the rear end of the cylinder through the sleeve three 17 and the flow hole 13 on the piston rod 3. The wire retaining ring on the inner wall of the rear end of the sleeve three 17 abuts with the last outer limit ring 8 on the outer wall of the piston rod 3. Therefore, the sleeve three 17 drives the piston rod 3 to extend. When the piston rod 3 is extended, the hydraulic oil in the cylinder cavity 19 between the sleeve three 17 and the piston rod 3 enters the rear end of the cylinder through the flow hole 13 on the piston rod 3. In this process, the sleeve one 15, the sleeve two 16, the sleeve three 17 and the piston rod 3 are basically extended forward synchronously. When the outer limit ring 8 at the front end of sleeve 15 abuts against the inner limit ring 6 on the outer cylinder 2, sleeve 15 reaches the limit extension position and sleeve 15 stops moving. At this time, the hydraulic oil at the rear end of the cylinder pushes sleeve 2 16 to move forward. When sleeve 2 16 moves forward, it continues to drive sleeve 3 17 and piston rod 3 to move forward, that is, sleeve 3 17 and piston rod 3 move forward synchronously with sleeve 2 16. When the outer limit ring 8 at the front end of sleeve 2 16 abuts against the inner limit ring 6 on sleeve 1 15, sleeve 2 16 reaches the limit extension position and sleeve 2 16 stops moving. At this time, the hydraulic oil at the rear end of the cylinder pushes sleeve 2 16 to move forward. The movable sleeve three 17 moves forward, and the sleeve three 17 continues to drive the piston rod 3 to move forward while moving forward, that is, the piston rod 3 and the sleeve three 17 move forward synchronously. When the outer limit ring 8 at the front end of the sleeve three 17 abuts against the inner limit ring 6 on the sleeve two 16, the sleeve three 17 reaches the limit extension position, and the sleeve three 17 stops moving. At this time, the hydraulic oil at the rear end of the cylinder pushes the piston rod 3 to move forward. When the outer limit ring 8 at the front end of the piston rod 3 abuts against the inner limit ring 6 on the sleeve three 17, the piston rod 3 reaches the limit extension position, and the piston rod 3 stops moving, thereby realizing the lifting action of the multi-stage lifting cylinder.

[0029] When the piston rod 3 and the sleeve are retracted, the oil port 1 loses pressure and is in an oil-discharging state. The piston rod 3 moves toward the rear end of the cylinder under the action of the lifted car and its own weight, and the hydraulic oil in the cylinder flows out from the oil port 1. The hydraulic oil at the rear end of the cylinder enters the cylinder cavity 19 between the piston rod 3 and the sleeve three 17 through the flow hole 13 on the piston rod 3. When the last outer limit ring 8 on the outer wall of the piston rod 3 abuts against the retaining ring 10 on the inner wall of the rear end of the sleeve three 17, the piston rod 3 drives the sleeve three 17 to move toward the rear end of the cylinder, and the hydraulic oil enters the cylinder cavity 19 between the sleeve three 17 and the sleeve two 16 through the flow hole 13 on the piston rod 3 and the sleeve three 17. When the retaining ring 10 on the inner wall at the rear end of the sleeve 2 16 abuts, the sleeve 3 17 drives the sleeve 2 16 to move toward the rear end of the cylinder, and the hydraulic oil enters the sleeve cavity 19 between the sleeve 2 16 and the sleeve 1 15 through the piston rod 3, the sleeve 3 17 and the flow hole 13 on the sleeve 2 16; when the last outer limit ring 8 on the outer wall of the sleeve 2 16 abuts against the retaining ring 10 on the inner wall at the rear end of the sleeve 15, the sleeve 2 16 drives the sleeve 1 15 to move toward the rear end of the cylinder, and the hydraulic oil enters the sleeve cavity 19 between the sleeve 1 15 and the outside through the piston rod 3, the sleeve 3 17, the sleeve 2 16 and the flow hole 13 on the sleeve 15; when the rear end of the sleeve 15 abuts against the cylinder bottom 18, the retraction of the piston rod 3 and the sleeve is completed.

[0030] The multi-stage lifting cylinders of dump trucks in the prior art are basically similar in structure. Figure 4As shown, a piston rod 3 is arranged in the center of an outer cylinder 2 with a closed rear end, and a sleeve 15 and a sleeve 2 16 are arranged between the outer cylinder 2 and the piston rod 3. The outer walls of the sleeves 15 and 16 at the rear end are integrally provided with a step 21 protruding outward, and a groove is formed between adjacent steps 21 for setting a support ring 12; in addition, a guide sleeve 20 for installing a guide seal 4 is welded to the front end of the sleeves 15 and 16, and the guide sleeve 20 also has a step protruding inward relative to the sleeve as an inner limit structure. In order to ensure that the multi-stage cylinder can be extended in sequence, steps need to be set at each level of the sleeve structure to play a limit role, so the sleeve is often welded by two sections of material. This structure is complicated to process, and two sections of material need to be processed first, and then welded. There is a large waste of materials, high cost, and no price advantage. There is a step protruding outward on the outer circle of the sleeve, which can only be processed by an external cylindrical grinder, and the processing efficiency is low. There is also a step hole on the inner hole of the sleeve, and the inner hole can only be rolled and formed before welding, so there are problems such as welding deformation. Therefore, this type of multi-stage lifting oil cylinder in the prior art has defects such as welding deformation and large processing errors. It is difficult to ensure the inner and outer round straightness of each level of cylinder barrel, resulting in uneven friction between each level of sleeve when the multi-stage cylinder is extended and retracted, and disorder will occur when the multi-stage cylinder is extended. When the disorder is serious, the impact force on the car body is increased, and safety accidents will also occur. The multi-stage sleeves of the utility model all adopt a uniform wall thickness structure, and no raised step-shaped structure is set on the inner wall and outer wall of the sleeve. The inner limit structure located on the inner wall of the sleeve is obtained by machining an inner limit groove on the inner wall of the sleeve and setting an inner limit ring in the inner limit groove; the guide seal located at the front end of the inner wall of the sleeve is installed in the sealing groove of the inner wall of the sleeve; the outer limit structure located on the outer wall of the sleeve is obtained by machining an outer limit groove on the outer wall of the sleeve and setting an outer limit ring in the outer limit groove; the support ring located on the outer wall of the sleeve is positioned by two outer limit rings on the outer wall of the sleeve. In this way, the inner wall and the outer wall of the sleeve do not have a step-like structure protruding from the reference cylinder wall, and compared with the prior art, the guide sleeve welded to the front end of the sleeve is eliminated. The sleeve of the utility model can be obtained by one-time processing of a pipe without welding, which is not only convenient and low-cost to process, but also will not cause deformation of the sleeve due to welding, effectively solving the defects of welding deformation and large processing errors in the prior art multi-stage lifting oil cylinder, and the difficulty in ensuring the straightness of the inner and outer circles of each stage cylinder, resulting in uneven friction between the sleeves at each stage when the multi-stage cylinder is extended and retracted, and disorder will occur when the multi-stage cylinder is extended, and serious disorder will increase the impact force on the carriage and cause safety accidents.

[0031] In addition to the above-mentioned embodiments, within the scope disclosed in the claims and the specification of the utility model, the technical features or technical data of the utility model can be reselected and combined to form new embodiments, which can be achieved by those skilled in the art without creative work. Therefore, these embodiments that are not described in detail in the utility model should also be regarded as specific embodiments of the utility model and within the protection scope of the utility model.

Claims

1. A multi-stage lifting cylinder, comprising an outer cylinder with a closed rear end and an oil port and a piston rod arranged at the center of the outer cylinder, characterized in that: A plurality of retractable sleeves are arranged between the outer cylinder and the piston rod. The sleeve is a structure of uniform wall thickness as a whole. The inner wall at the front end of the sleeve is provided with a plurality of sealing grooves for fixing the guide seal. The inner wall at the front end of the sleeve behind the sealing groove is provided with an inner limiting groove for fixing the inner limiting ring. The outer wall at the rear end of the sleeve is provided with an outer limiting groove for fixing the outer limiting ring. The inner wall at the rear end of the sleeve is also provided with a retaining ring groove for fixing the retaining ring.

2. The multi-stage lifting cylinder according to claim 1, characterized in that: The outer cylinder is of uniform wall thickness structure, a plurality of sealing grooves for fixing guide seals are arranged on the inner wall of the front part of the outer cylinder, an inner limiting groove is arranged on the inner wall of the outer cylinder behind the sealing groove, and an inner limiting ring is arranged in the inner limiting groove.

3. The multi-stage lifting cylinder according to claim 1, characterized in that: A plurality of outer limiting grooves are arranged on the outer wall of the rear part of the piston rod, and an outer limiting ring is arranged in the outer limiting groove.

4. The multi-stage lifting cylinder according to claim 1, 2 or 3, characterized in that: There are three outer limiting rings, and a supporting ring is arranged between the two outer limiting rings located at the rear side.

5. The multi-stage lifting cylinder according to claim 4, characterized in that: The rear wall of the sleeve is provided with flow holes, the center of the rear end of the piston rod is provided with a cavity, the cavity wall of the cavity is provided with flow holes, and the flow holes are located between the two outer limit rings on the front side.

6. The multi-stage lifting cylinder according to claim 4, characterized in that: There are two supporting rings between the two outer limiting rings on the sleeve and the piston rod, and the total width of the two supporting rings is matched with the width of the gap between the two outer limiting rings.

7. The multi-stage lifting cylinder according to claim 1, characterized in that: The retaining ring groove is located at the rear side of the outer limiting groove, the retaining ring groove is semicircular and its front groove wall is provided with an inclined surface, the retaining ring is a wire retaining ring, and the depth of the retaining ring groove is less than the wire diameter of the wire retaining ring.

8. The multi-stage lifting cylinder according to claim 1 or 2, characterized in that: The inner limiting ring is one and is arranged close to the guide seal at the front end.

9. The multi-stage lifting cylinder according to any one of claims 1, 2, 3 or 7, characterized in that: The sealing groove comprises a wide groove and narrow grooves located on both sides of the wide groove, and the lengths of the cylinder walls between two adjacent sealing grooves are the same.

Images