hydraulic cylinder

Abstract

This invention provides a hydraulic cylinder, comprising a connecting sleeve, a connecting plate, and a cylinder barrel arranged coaxially and welded sequentially at their ends. The cylinder barrel contains a piston, a piston rod, a sealing plug, and a guide rod. The piston divides the cylinder barrel's inner cavity into a rod-side cavity and a rodless cavity, both connected to external oil passages. The piston rod extends axially within the rod-side cavity and connects to the piston; the piston rod is hollow and forms an axially extending receiving cavity. The sealing plug is located within the receiving cavity and divides it into an oil storage cavity and an air cavity. The guide rod is coaxially arranged and installed within the oil storage cavity, with one end movably penetrating the piston and connecting to the connecting plate, and the other end abutting against the sealing plug. The guide rod, along with the sealing plug, can move relative to the piston rod. This invention reduces the volume of the main engine oil tank by providing an oil storage cavity within the piston rod's receiving cavity. Furthermore, the connecting sleeve, welded to the connecting plate, allows for extended cylinder installation distances without altering the cylinder's working stroke, facilitating disassembly.

Description

Technical Field

[0001] This invention belongs to the field of engineering machinery technology, and in particular relates to a hydraulic cylinder. Background Technology

[0002] Hydraulic cylinders offer advantages such as high output power, high working efficiency, stable and reliable performance, and convenient use and maintenance. However, in main unit applications, external oil tanks are often required, especially for ultra-large truck cranes, where the cylinder specifications are relatively large. Therefore, the hydraulic oil required for cylinder operation is also relatively large, necessitating a larger oil tank. This results in an overall bulky main unit, failing to meet industry requirements for lightweight construction. To reduce the weight of the main unit, the piston rod in the hydraulic cylinder is typically designed with an oil storage structure. However, in existing technologies, hydraulic cylinders with oil storage functions usually have an unchanged installation distance, and the core rod in the hydraulic cylinder is fixed to the piston end with bolts, making it unsuitable for applications where the initial installation distance is much greater than the stroke. Summary of the Invention

[0003] The main objective of this invention is to provide a hydraulic cylinder that addresses the technical problem that existing hydraulic cylinders cannot be used in situations where the initial installation distance is much greater than the cylinder stroke.

[0004] To achieve the above objectives, the present invention provides a hydraulic cylinder comprising a connecting sleeve, a connecting plate, and a cylinder barrel arranged coaxially and welded sequentially at their ends; wherein, the cylinder barrel contains:

[0005] piston;

[0006] A piston rod extends axially and is connected to the piston; the piston rod is hollow and has an axially extending receiving cavity.

[0007] A sealing plug is disposed within the receiving cavity and divides the receiving cavity into an oil storage cavity and an air cavity; and

[0008] A guide rod is coaxially installed in the oil storage chamber, with one end movably passing through the piston and connected to the connecting plate, and the other end abutting against the sealing plug. The sealing plug is fixed on the guide rod and moves relative to the piston rod.

[0009] In an embodiment of the present invention, the bottom wall of the rodless cavity is provided with a through-hole for the guide rod to pass through in a sealed manner. The bottom end of the guide rod passes through the piston and the through-hole in sequence and is flexibly connected to the connecting plate through a pin assembly.

[0010] In an embodiment of the present invention, the pin assembly includes a spherical bearing and a pin that overfits the spherical bearing. The end of the guide rod has a first through hole. The spherical bearing is circumferentially mounted on the inner sidewall of the first through hole. The connecting plate has a second through hole that clearance fits the pin. The pin passes through the spherical bearing and the second through hole in sequence and connects the guide rod and the connecting plate.

[0011] In an embodiment of the present invention, a support ring is circumferentially sealed around the inner wall of the second through hole, and the pin seal passes through the support ring.

[0012] In an embodiment of the present invention, the support ring is filled with a compressible polytetrafluoroethylene material.

[0013] In an embodiment of the present invention, cover plates are sealed at both ends of the pin.

[0014] In an embodiment of the present invention, the piston divides the inner cavity of the cylinder into a rod chamber and a rodless chamber, both of which are connected to an external oil passage. The piston is provided with a plurality of hydraulic oil exchange holes for the hydraulic oil in the oil storage chamber to flow to the rodless chamber.

[0015] In an embodiment of the present invention, a guide sealing ring is installed at the through contact portion between the guide core rod and the piston.

[0016] In an embodiment of the present invention, the end of the guide rod away from the piston is connected to the sealing plug by a fastener and extends into the air chamber. The two ends of the sealing plug are respectively connected to sealing connecting plates extending toward the inner wall of the receiving cavity. Both sealing connecting plates are sealed and fitted against the inner wall of the receiving cavity and can move relative to each other.

[0017] In an embodiment of the present invention, the air chamber is provided with a pressure balancing component for balancing the pressure of the air chamber and the oil storage chamber.

[0018] In an embodiment of the present invention, the pressure balancing component is an air inlet pipe, which penetrates the side wall of the piston rod from the outside and extends into the air chamber to introduce or discharge gas in the air chamber.

[0019] Through the above technical solutions, the hydraulic cylinder provided in the embodiments of the present invention has the following beneficial effects:

[0020] A piston and a piston rod connected to the piston are installed in the inner cavity of the cylinder. The piston divides the inner cavity of the cylinder into a rodless cavity and a rod cavity. The piston rod is hollow and forms a receiving cavity. A sealing plug is installed in the receiving cavity and the receiving cavity is divided into an oil storage cavity and an air cavity for storing hydraulic oil.

[0021] When the hydraulic cylinder is working, the rodless chamber is connected to the external oil circuit and draws hydraulic oil from the external hydraulic system, increasing its volume. By movably installing the guide rod inside the piston rod, and allowing the guide rod and the sealing plug to move relative to the piston rod, the distance between the bottom end of the guide rod and the sealing plug remains constant. When the piston drives the piston rod to move upwards, the volume of the entire oil reservoir decreases, allowing the hydraulic oil in the reservoir to enter and supply the rodless chamber. Throughout this process, the reservoir provides a large portion of the hydraulic oil to the rodless chamber, while the rodless chamber only needs to draw a small amount from the external hydraulic system. This reduces the overall volume of the hydraulic cylinder's oil tank, achieving weight reduction. Furthermore, this invention achieves the goal of extending the cylinder's installation distance without changing the cylinder's working stroke by welding a connecting plate and a connecting sleeve to the bottom of the cylinder barrel. This structure is also easy to disassemble.

[0022] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0023] The accompanying drawings are provided to illustrate the invention and form part of the specification. They are used together with the following detailed description to explain the invention, but do not constitute a limitation thereof. In the drawings:

[0024] Figure 1 This is a cross-sectional schematic diagram of a hydraulic cylinder according to an embodiment of the present invention;

[0025] Figure 2 This is a partial structural schematic diagram of a hydraulic cylinder according to an embodiment of the present invention;

[0026] Figure 3 This is a front view schematic diagram of a hydraulic cylinder according to an embodiment of the present invention.

[0027] Explanation of reference numerals in the attached figures

[0028] Detailed Implementation

[0029] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0030] The hydraulic cylinder according to the present invention is described below with reference to the accompanying drawings.

[0031] like Figure 1 and Figure 3 As shown, in an embodiment of the present invention, a hydraulic cylinder is provided, comprising a connecting sleeve 10, a connecting plate 20, and a cylinder barrel 30 arranged coaxially and welded sequentially at their ends; wherein, the cylinder barrel 30 is provided with:

[0032] The piston 32 divides the inner cavity of the cylinder 30 into a rod chamber 34 and a rodless chamber 35, both of which are connected to the external oil passage. The rod chamber 34 and the rodless chamber 35 are both connected to the external oil passage through the oil pipe 70.

[0033] The piston rod 31 extends axially and is arranged in the rod cavity 34 and connected to the piston 32. The piston rod 31 is hollow and forms an axially extending receiving cavity.

[0034] The sealing plug 36 is disposed within the receiving cavity and divides the receiving cavity into an oil storage cavity 60 and an air cavity 80; and

[0035] The guide rod 33 is coaxially arranged with the piston rod 31 and installed in the oil reservoir 60. One end of the guide rod 33 moves through the piston 32 and is connected to the connecting plate 20, while the other end abuts against the connecting sealing plug 36. The guide rod 33 can move relative to the piston rod 31 together with the sealing plug 36.

[0036] When the hydraulic cylinder is working, the rodless chamber 35 is connected to the external oil circuit and absorbs a small amount of hydraulic oil from the external hydraulic system, which increases the volume of the rodless chamber 35. Driven by the hydraulic oil, the piston 32 moves the piston rod 31 to the right, causing the piston rod 31 to extend outward from the cylinder 30 to support the external actuator. Since the guide rod 33 is movably installed inside the piston rod 31 and can move relative to the piston rod 31, the distance between the bottom end of the guide rod 33 and the sealing plug 36 remains constant. When the piston 32 moves to the right, the volume of the entire oil reservoir 60 decreases, allowing the hydraulic oil in the oil reservoir 60 to enter the rodless chamber 35 and provide hydraulic oil. Throughout the process, the oil reservoir 60 provides a large portion of the hydraulic oil to the rodless chamber 35, while the rodless chamber 35 only needs to absorb a small amount of hydraulic oil from the external hydraulic system. This reduces the overall volume of the hydraulic cylinder's oil tank, achieving the goal of weight reduction. During the retraction of piston rod 31, the volume of air chamber 80 decreases and gas is discharged, completing the retraction process. At this time, piston 32 drives piston rod 31 to move to the left, making the volume of the entire rodless chamber 35 smaller. This forces the hydraulic oil in the rodless chamber 35 into the oil reservoir 60, increasing the volume of the oil reservoir 60.

[0037] In this invention, the guide rod 33 serves as a guide and load-bearing element, guiding the piston 32 to drive the piston rod 31 to extend and retract. The guide rod 33 is a solid rod; by making it a solid rod, its load-bearing capacity is increased, improving the overall load-bearing performance of the hydraulic cylinder, while its radial dimension is reduced, increasing the volume of the oil reservoir 60. Furthermore, to maintain connection stability, the connecting sleeve 10, connecting plate 20, and cylinder 30 are all cylindrical structures with consistent diameters. This coaxial arrangement of the connecting sleeve 10, connecting plate 20, and cylinder 30 results in a more aesthetically pleasing overall streamline and facilitates welding operations.

[0038] This invention provides an oil storage chamber 60 for storing hydraulic oil within the receiving cavity of the piston rod 31. When the piston rod 31 of the hydraulic cylinder extends outward from the cylinder barrel 30 and operates, the hydraulic oil in the oil storage chamber 60 is supplied to the rodless cavity 35. This increases the volume of the oil storage chamber 60 and improves the hydraulic cylinder's own oil storage capacity, thereby reducing the volume of the main unit's oil tank and achieving the goal of lightweight design for the main unit.

[0039] Furthermore, the connecting sleeve 10 can be connected to the connecting plate 20 by welding or other means, so that the working stroke of the hydraulic cylinder is not changed when the installation distance of the hydraulic cylinder is extended. In other words, although the stroke (i.e., the extension and retraction) of the hydraulic cylinder remains unchanged, the installation distance can be changed by changing the length of the connecting plate 20. For example, some models only require such a long hydraulic cylinder stroke, but the installation stroke of the main unit is relatively long. In this case, the installation stroke can be adjusted by using the connecting plate 20.

[0040] In an embodiment of the present invention, the bottom wall of the rodless cavity 35 is provided with a through-hole for the guide core rod 33 to pass through in a sealed manner. The bottom end of the guide core rod 33 passes through the piston 32 and the through-hole in sequence and is flexibly connected to the connecting plate 20 through the pin assembly 40.

[0041] In embodiments of the present invention, such as Figure 2 As shown, the pin assembly 40 includes a spherical bearing 41 and a pin 42 that overfits with the spherical bearing 41. A first through hole is provided at the end of the guide rod 33. The spherical bearing 41 is circumferentially mounted around the inner wall of the first through hole. A second through hole with a clearance fit to the pin 42 is provided on the connecting plate 20. The pin 42 passes through the spherical bearing 41 and the second through hole sequentially, connecting the guide rod 33 and the connecting plate 20. During installation, the pin 42 is sequentially passed through the spherical bearing 41 and the second through hole in a direction perpendicular to the guide rod 33 and locked, thereby achieving the purpose of fixing the guide rod 33 and the connecting plate 20. To ensure the connection stability of the pin 42 and the guide rod 33, the outer peripheral wall of the pin 42 contacts and overfits with the inner wall of the spherical bearing 41, and the spherical bearing 41 is preferably a universal joint.

[0042] In an embodiment of the present invention, a support ring 43 is circumferentially sealed around the inner wall of the second through hole, and the pin 42 sealably passes through the support ring 43. There are two support rings 43, symmetrically distributed near the two ends of the pin 42. The support rings 43 connect the pin 42 and the connecting plate 20, and the support rings 43 are filled with elastically compressible polytetrafluoroethylene material, giving the support rings 43 a certain amount of compression. This allows the pin 42 to have a certain range of motion. Since the guide rod 33 is completely fixed, while the pin 42 has room to move, the installation of the guide rod 33 is relatively easy, thus achieving a flexible connection between the guide rod 33 and the connecting plate 20. This allows the guide rod 33 to float within a small range, eliminating the constriction that occurs when the piston rod 31 and the guide rod 33 are not coaxial, preventing vibration and abnormal noise during the extension and retraction of the hydraulic cylinder piston rod 31. Simultaneously, it also reduces processing requirements and assembly difficulty.

[0043] In an embodiment of the present invention, cover plates 44 are sealed at both ends of the pin 42. Furthermore, sealing components are also provided on the cover plates 44 to ensure the cleanliness and sealing of the entire hydraulic cylinder interior. Gaps are left between the pin 42 and the cover plates 44 and the connecting plate 20; that is, the pin 42 has gaps except when it contacts the support ring 43 and the spherical bearing 41.

[0044] In an embodiment of the present invention, the piston 32 is provided with multiple hydraulic oil exchange holes for the hydraulic oil in the oil reservoir 60 to flow through. When the piston rod 31 extends out of the cylinder 30 to work, the hydraulic oil in the oil reservoir 60 enters the rodless chamber 35 through the hydraulic oil exchange holes on the piston 32, thereby exchanging hydraulic oil between the oil reservoir 60 and the rodless chamber 35. When the piston rod 31 retracts, the hydraulic oil in the rodless chamber 35 enters the oil reservoir 60 through the hydraulic oil exchange holes on the piston 32 for storage, so that it can be used for the next exchange.

[0045] In an embodiment of the present invention, a guide sealing ring 50 is installed at the through contact portion between the guide rod 33 and the piston 32, so that when the piston 32 and the guide rod 33 move relative to each other, the sealing of the entire oil storage chamber 60 can be guaranteed.

[0046] In an embodiment of the present invention, the end of the guide rod 33 away from the piston 32 is connected to the sealing plug 36 by fasteners and extends into the air chamber 80. The two ends of the sealing plug 36 are respectively connected to sealing connecting plates 90 extending toward the inner sidewall of the receiving cavity. Both sealing connecting plates 90 are sealed and fit against the inner sidewall of the receiving cavity and can move relative to each other.

[0047] In an embodiment of the present invention, the air chamber 80 is provided with a pressure balancing component for balancing the pressure of the air chamber 80 and the oil storage chamber 60.

[0048] In an embodiment of the present invention, the pressure balancing component is an intake pipe 81. The intake pipe 81 penetrates the side wall of the piston rod 31 from the outside and extends into the air chamber 80 to introduce or discharge gas into the air chamber 80. When the volume of the oil storage chamber 60 changes, in order to balance the pressure between the oil storage chamber 60 and the air chamber 80, the intake pipe 81 delivers external gas into the air chamber 80 or discharges gas from the air chamber 80 through the intake pipe 81. In other embodiments, ventilation holes or other structural forms can be provided on the side wall of the air chamber 80, as long as pressure balance between the air chamber 80 and the oil storage chamber 60 can be achieved.

[0049] Furthermore, the hydraulic cylinder also includes a cylinder bottom and a cylinder head, with the cylinder bottom installed at the bottom of the connecting cylinder 10 and the cylinder head installed at the top of the cylinder barrel 30.

[0050] In the description of this invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0051] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0052] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0053] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A hydraulic cylinder, characterized in that, The hydraulic cylinder includes a connecting sleeve (10), a connecting plate (20), and a cylinder (30) arranged coaxially and connected end to end in sequence. The connecting plate (20) is connected to the bottom end of the cylinder (30), and the connecting sleeve (10) is connected to the end of the connecting plate (20) opposite to the cylinder (30), for extending the installation distance of the hydraulic cylinder without changing its working stroke; wherein, the cylinder (30) is provided with: Piston (32); A piston rod (31) extends axially and is connected to the piston (32). The piston rod (31) is hollow and has an axially extending receiving cavity. A sealing plug (36) is disposed within the receiving cavity and divides the receiving cavity into an oil storage cavity (60) and an air cavity (80); and A guide rod (33) is coaxially mounted in the oil reservoir (60), with one end movably passing through the piston (32) and connected to the connecting plate (20), and the other end abutting against the sealing plug (36). The sealing plug (36) is fixed on the guide rod (33) and moves relative to the piston rod (31). The bottom wall of the rodless cavity (35) has a through-hole for the guide rod (33) to pass through in a sealed manner. The bottom end of the guide rod (33) passes through the piston (32) and the through-hole in sequence and is flexibly connected to the connecting plate (20) through a pin assembly (40). The pin assembly (40) includes a spherical bearing (41) and a pin (42) that overfits the spherical bearing (41). The guide rod (33) has a first through hole at its end. The spherical bearing (41) is circumferentially mounted on the inner wall of the first through hole. The connecting plate (20) has a second through hole that is clearance-fitted with the pin (42). The pin (42) passes through the spherical bearing (41) and the second through hole in sequence and connects the guide core rod (33) and the connecting plate (20). The inner wall of the second through hole is circumferentially sealed with a support ring (43). The pin (42) passes through the support ring (43) in a sealed manner. The support ring (43) is filled with elastically compressible polytetrafluoroethylene material so that the pin (42) has a certain range of movement. The two ends of the pin (42) are sealed with cover plates (44).

2. The hydraulic cylinder according to claim 1, characterized in that, The piston (32) divides the inner cavity of the cylinder (30) into a rod chamber (34) and a rodless chamber (35) that are both connected to the external oil circuit. The piston (32) has multiple hydraulic oil exchange holes for the hydraulic oil in the oil storage chamber (60) to flow to the rodless chamber (35).

3. The hydraulic cylinder according to claim 1, characterized in that, A guide sealing ring (50) is installed at the through contact point between the guide core rod (33) and the piston (32).

4. The hydraulic cylinder according to claim 1, characterized in that, The end of the guide rod (33) away from the piston (32) is connected to the sealing plug (36) by a fastener and extends into the air chamber (80). The two ends of the sealing plug (36) are respectively connected to sealing connecting plates (90) extending toward the inner wall of the receiving cavity. Both sealing connecting plates (90) are sealed and fit against the inner wall of the receiving cavity and can move relative to each other.

5. The hydraulic cylinder according to claim 1, characterized in that, The air chamber (80) is provided with a pressure balancing component for balancing the pressure of the air chamber (80) and the oil storage chamber (60).

6. The hydraulic cylinder according to claim 5, characterized in that, The pressure balancing component is an air inlet pipe (81), which penetrates the side wall of the piston rod (31) from the outside and extends into the air chamber (80) to introduce or discharge gas in the air chamber (80).

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