RELATED APPLICATION

[0001] The present application claims priority to co-pending U.S. Provisional Patent Application No. 61/787,868, filed March 15, 2013, the entire contents of which is hereby incorporated by reference.

FIELD

[0002] This present invention relates to hydraulic cylinder assemblies and, more particularly to a self-contained and/or modular hydraulic cylinder assembly.

SUMMARY

[0003] In some aspects, a hydraulic cylinder assembly (including a pump powered by an electric motor) includes an oil reservoir or container in the housing and surrounding the hydraulic cylinder tube. By providing the oil reservoir around the piston, an aluminum extrusion can be used, resulting in a small size unit.

[0004] In some constructions, the oil reservoir is one where a movable wall separates the storage space into an oil side and an air side. A spring biases the movable wall toward the oil side of the reservoir. The spring-loaded wall keeps the oil available to the hydraulic cylinder at all times, no matter what the unit orientation.

[0005] In some constructions, more than one oil reservoir space can be included in the housing, with each space having its own spring biased wall for separating the oil from an air side and for keeping the oil available to the hydraulic circuit.

[0006] The hydraulic circuit includes a restriction orifice to ensure that the fluid and cylinder move together, when force is applied to the piston. When fluid flows in the opposite direction, however, a bypass check valve allows fluid to flow around the orifice. The hydraulic circuit is internally blocked after piston rod extension or retraction by closing pilot operated check valves.

[0007] In some uses and applications, the piston needs to provide less force but faster extension or retraction. In other instances, more force and slower piston movement is needed. This modular unit accommodates both situations by allowing for the insertion of a cylinder tube into the piston bore. The cylinder tube is sealed by O-rings at its top and bottom. When the cylinder tube is in the piston bore, a smaller diameter piston can be used. This provides less force but higher speed for a given size motor. When more force but slower speed is needed, the cylinder tube is removed, and a larger diameter piston providing more force but slower speed, is used.

[0008] The motor is connected to the cylinder housing so that the motor is parallel to the cylinder housing. The hydraulic pump valves are situated at one end of the electric motor and adjacent one end of the hydraulic piston housing.

[0009] The housing aluminum extrusion also provides, in addition to the piston bore and the oil reservoir, a channel for a hydraulic pull tube.

[0010] In some constructions, position sensors can be incorporated into the cylinder housing to indicate the position of the piston rod.

[0011] In one independent aspect, a housing assembly for a hydraulic cylinder assembly including a piston is provided. The housing assembly may generally include a housing with an outer wall extending along and about an axis; and an interior wall at least partially defining a tube extending along the axis and operable to receive the piston, and a container extending along the axis and for hydraulic fluid for operating the cylinder assembly.

[0012] In another independent aspect, a hydraulic cylinder assembly may generally include a piston; and a housing assembly including a housing with an outer wall extending along and about an axis; and an interior wall at least partially defining a tube extending along the axis and operable to receive the piston, and a container extending along the axis and for hydraulic fluid for operating the cylinder assembly.

[0013] In yet another independent aspect, a hydraulic cylinder assembly may generally include a housing assembly with a housing defining a tube having a first diameter and extending along an axis, and a cylindrical tube selectively insertable into the tube and having a second diameter; a first piston having the first diameter; and a second piston having a second diameter. In a first configuration of the cylinder assembly, the first piston is insertable into the tube, and, in a second configuration of the cylinder assembly, the cylindrical tube is insertable into the tube and the second piston is insertable into the cylindrical tube. The cylinder assembly is selectively and alternatively arranged in the first configuration and in the second configuration. [0014] In a further independent aspect, a method of manufacturing a housing assembly for a cylinder assembly including a piston is provided. The method may generally include forming (e.g., extruding) a housing including an outer wall extending along and about an axis, and an interior wall at least partially defining a tube extending along the axis and operable to receive the piston, and a container extending along the axis and for hydraulic fluid for operating the cylinder assembly.

[0015] In another independent aspect, a method of manufacturing a hydraulic cylinder assembly is provided. The method may generally include forming (e.g., extruding) a housing including an outer wall extending along and about an axis, and an interior wall at least partially defining a tube extending along the axis, and a container extending along the axis and for hydraulic fluid for operating the cylinder assembly; and supporting a piston in the tube.

[0016] In yet another independent aspect, a method of assembling a hydraulic cylinder assembly is provided. The method may generally include providing a housing assembly including a housing defining a tube having a first diameter and extending along an axis, and a cylindrical tube selectively insertable into the tube and having a second diameter; providing a first piston having the first diameter and a second piston having a second diameter; assembling a first configuration of the cylinder assembly including inserting the first piston into the tube; assembling a second configuration of the cylinder assembly including inserting the cylindrical tube into the tube and the second piston into the cylindrical tube. The cylinder assembly is selectively and alternatively arranged in the first configuration and in the second configuration.

[0017] Independent features and independent advantages of the invention will become apparent to those skilled in the art upon review of the detailed description, drawings and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Fig. 1 is a perspective view of a hydraulic cylinder assembly. [0019] Fig. 2 is a schematic view of the cylinder assembly of Fig. 1 .

[0020] Fig. 3 is a perspective view of the cylinder assembly of Fig. 1 , with the pump housing shown as being transparent.

[0021] Fig. 4 is a perspective view of the cylinder assembly of Fig. 1 , with the end wall shown as being transparent. [0022] Fig. 5 is an enlarged perspective view of a portion of the cylinder assembly shown in Fig. 4.

[0023] Fig. 6 is a perspective view of the cylinder assembly of Fig. 1 , with the housing outer wall shown as being transparent.

[0024] Fig. 7 is a perspective view of the cylinder assembly of Fig. 1 , with the housing outer and interior walls shown as being transparent.

[0025] Fig. 8 is a perspective cross-sectional view of the cylinder assembly of Fig. 1 and illustrating an alternative configuration of the cylinder assembly.

DETAILED DESCRIPTION

[0026] Before any independent embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other independent embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. Use of "including" and "comprising" and variations thereof as used herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Use of "consisting of" and variations thereof as used herein is meant to encompass only the items listed thereafter and equivalents thereof.

[0027] A hydraulic cylinder assembly 10 is illustrated in Figs. 1 -8. In the illustrated construction, the cylinder assembly 10 generally provides a self-contained linear drive unit. In some aspects, as described below, the cylinder assembly 10 may be a modular assembly capable of various configurations which include at least some common components. The illustrated cylinder assembly 10 generally includes (see Fig. 7) a housing assembly 14 defining a cylinder tube 18 and a reservoir or container 22 for hydraulic fluid (e.g., oil), a piston 26 supported in the tube 18, a pump 30, and a motor 34.

[0028] The housing assembly 14 includes (see Fig. 8) a housing 38 with an outer wall 42 and a cylindrical interior wall 46 defining the tube 18. The interior wall 46 cooperates with the outer wall 42 and container walls 50 to define the container 22. The housing 38 also includes a conduit 54, and, in the illustrated construction, the interior wall 46 cooperates with a conduit wall 58 to define the conduit 54. Connecting walls 62 connect the tube 18 and the conduit 54 to the outer wall 42. The container walls 50 and the connecting walls 62 provide support to the interior wall 46 and tube 18.

[0029] A piston 66 (see Figs. 6-7) is arranged in the container 22 to define separate fluid and air sides of the container 22. A spring 70 biases the piston 66 to pressurize the fluid in the container 22 so that fluid can be supplied and the cylinder assembly 10 can be operated in any orientation relative to the ground (e.g., vertical with the fluid side of the container 22 below or above the air side, horizontal, etc.).

[0030] The housing 38 may define more than one container 22a, 22b..., 22n. The interior wall 46 may cooperate with the outer wall 42 and the connecting wall(s) 62 to define the additional container(s) 22b...22n. Each additional container 22b...22n may include a wall (e.g., a spring-biased piston (not shown but similar to the piston 66 and spring 70)) separating its fluid and air sides.

[0031] The housing assembly 14 also includes end walls 74, 78 at opposite ends (a base end and a rod end, respectively) of the housing 38. Each end wall 74, 78 closes the associated end of the housing 38. Fasteners 82 engage in respective openings 86, 90 provided in the housing 38 and the end walls 74, 78 to connect the end walls 74, 78 to the housing 38.

[0032] The base end wall 74 includes a mounting member 94 to connect the cylinder assembly 10 to a support (not shown). The rod end wall 78 defines an opening 98 for receiving a rod 102 of the piston 26. The rod 102 includes a similar mounting member 106 to connect the cylinder assembly 10 to a relatively movable structure (not shown). The end wall 78 also provides a connector (e.g., a conduit, orifice, etc. (not shown)) to fluidly connect the rod end of the tube 18 to the conduit 54.

[0033] In the illustrated construction, the housing 38 is formed by extrusion from an extrudable material (e.g., aluminum). The housing 38 is extruded to provide the illustrated structure (e.g., the walls 42, 46, 50, 58 and/or 62, the openings 86, etc.) and components (e.g., the tube 18, the container 22, the conduit 54, etc.). As such, the housing 38, its structure and components extend along an axis X and are substantially parallel. [0034] In other constructions (not shown), the housing 38 may be formed by other processes and/or of other suitable materials. For example, the components (e.g., the tube 18, the container 22, the conduit 54, etc.) may be formed independently and then supported in the outer wall 42.

[0035] The illustrated tube 18 has an inner bore diameter (e.g., about 40 mm), and the piston 26 has a corresponding outer diameter (e.g., about 40 mm). As shown in Fig. 8, the housing assembly 14 also includes a separate cylindrical tube 1 10 which is insertable into the tube 18 and sealed (e.g., by O-rings (not shown)) at each end. The tube 1 10 has an inner bore diameter (e.g., about 32 mm) which is smaller than the bore diameter of the tube 18. The tube 1 10 receives a piston 1 14 having a corresponding diameter (e.g., about 32 mm) which, likewise, is smaller than the diameter of the piston 26. As explained below, the additional tube 1 10 provides modularity for the cylinder assembly 10.

[0036] The illustrated pump 30 (see Fig. 3) is a bi-directional pump including a housing 1 18, and the illustrated motor 34 is an electric motor. The pump 30 and the motor 34 (e.g., the motor output shaft 122) are mounted to the housing assembly 14 on a mount 124 and are arranged to extend parallel to the axis X of the housing 38. In the illustrated construction, the end wall 74 provides the mount 124 to which the pump housing 1 18 is connected to support the pump 30 and the motor 34 on the housing assembly 14.

[0037] The motor 34 includes an electrical connector (e.g., a cable 126) to connect the motor 34 to a power source (not shown). The cylinder assembly 10 may include one or more sensors (e.g., a reed switch (not shown)) to sense a position of the piston 26, 1 14 relative to the housing 38 (e.g., extended, retracted, intermediate) with, if necessary, associated cables (not shown).

[0038] The cylinder assembly 10 may be used with various pumps and motors to provide further modularity. For example, the motor 34 may be a 12V DC motor, a 24V DC motor, a 230V AC motor, etc., powered by an appropriate power source.

[0039] The cylinder assembly 10 also includes a hydraulic circuit 130 connecting the hydraulic components (e.g., the container(s) 22, the pump 30, the tube 18 and piston 26, 1 14). The circuit 130 includes a push side (A) and a pull side (B) and a pump directional valve 134 operable to direct fluid from the pump 30 to one side and from the other side to the container 22 (e.g., from the pump 30 to the push side (A) and from the pull side (B) to the container 22 to extend the piston 26, 1 14 relative to the housing 38 or vice versa to retract the piston 26, 1 14).

[0040] Each side of the circuit 130 includes a restriction orifice 138A, 138B and a bypass check valve 142A, 142B to allow fluid to flow around the orifice 138A, 138B. A pilot-operated check valve (POCV) 146A, 146B maintains the piston 26, 1 14 in position after the pump 30 stops operating, and, during operation, pressure applied to one side causes the POCV 146 on the other side to open. A pressure relief valve 150A, 150B is provided to adjust the maximum fluid pressure to limit the associated force (push- or pull-force), and a manual relief valve 154 is operable to bypass the POCVs 146A, 146B when electricity is not available to operate the motor 34 and thereby the pump 30.

[0041] The pump directional valve 134 and the POCVs 146A, 146B are supported in the pump housing 1 18. The orifices 138A, 138B, the bypass check valves 142A, 142B, the pressure relief valves 150A, 150B and the manual relief valve 154 are provided in the housing assembly 14. The components are supported at one end of the housing 38 (e.g., the base end from which the piston 26, 1 14 is extended). The conduit 54 connects the rod end of the tube 18, 1 10 to the components.

[0042] To assemble the cylinder assembly 10, in a first configuration, the larger-diameter piston 26 is supported in the tube 18 of the housing 38. The end walls 74, 78 are connected to the housing 38. A selected pump 30 and a selected motor 30 are mounted to the housing assembly 14 to provide the self-contained linear drive unit.

[0043] As mentioned above, the cylinder assembly 10 is modular. In a second

configuration, the tube 1 10 is inserted into the tube 18 and sealed. The smaller-diameter piston 1 14 is supported in the tube 1 10, and the remainder of the cylinder assembly 10 is assembled, as described above, to provide a second self-contained linear drive unit.

[0044] In operation of the selected cylinder assembly 10, the pump directional valve 134 is operated to provide extension or retraction of the piston 26, 1 14 relative to the housing 38. The motor 34 is powered and operates the pump 30 to supply fluid to the associated side of the piston 26, 1 14. If provided, the sensor(s) sense the position of the piston 26, 1 14 relative to the housing 38. When the pump 30 stops, the POCVs operate to maintain the position of the piston 26, 1 14. If electrical power is unavailable and adjustment of the position of the piston 26, 1 14 is desired, the manual relief valve 154 is operated. [0045] Generally, in a configuration with the larger diameter piston 26, the cylinder assembly 10 produces greater linear force compared to a configuration with the smaller diameter piston 1 14 (e.g., about 21 .5 kN compared to about 14 kN) which, on the other hand, operates (extends/retracts) with greater speed (e.g., about 1 1.5 mm/s compared to about 7.5 mm/s). The different configurations include common components (e.g., the housing 38, the end walls 74, 78, the pump 30, the motor 34) while providing different operating characteristics (e.g., linear force, operating speed).

[0046] One or more independent features and independent advantages of the invention may be set forth in the following claims: