BRIEF DESCRIPTION OF THE DRAWINGS
Other features and advantages of the present invention will become apparent in the following detailed description of the preferred embodiment with reference to the accompanying drawings, of which:.
FIG. 1 is a fragmentary schematic sectional view showing a conventional pneumatic cylinder device when a control valve thereof is in a closed position;
FIG. 2 is a fragmentary schematic sectional view showing the conventional pneumatic cylinder device when the control valve is in an opened position;
FIG. 3 is a fragmentary schematic sectional view showing the preferred embodiment of a pneumatic cylinder device according to the present invention when a control valve is in a closed position;
FIG. 4 is an exploded fragmentary perspective view showing an inner cylinder unit of the preferred embodiment;
FIG. 5 is a schematic sectional view taken along line V-V of FIG. 3 and only showing the inner cylinder unit; and
FIG. 6 is a fragmentary schematic sectional view showing the preferred embodiment when the control valve is in an opened position.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to FIG. 3, the preferred embodiment of a pneumatic cylinder device according to the present invention is shown to include a tubular outer cylinder 3, an inner cylinder unit, a piston unit 6, and a control valve unit 7.
The outer cylinder 3 is made of metal, and has first and second open ends 33, 34 opposite to each other in an axial direction (X).
Referring further to FIGS. 4 and 5, the inner cylinder unit is disposed in the outer cylinder 3, and includes an inner cylinder 4 and a flow passage formation plate 2.
The inner cylinder 4 is unitary, and is made of a rigid plastic material. The inner cylinder 4 has a tubular cylinder body 41 that defines an actuator-mounting space 45, an air chamber 43 opposite to the actuator-mounting space 45, and a valve-mounting space 44 disposed between the actuator-mounting space 45 and the air chamber 43. In this embodiment, the actuator-mounting space 45 and the air chamber 43 are respectively disposed adjacent to the first and second open ends 33, 34 of the outer cylinder 3, as shown in FIG. 3. The valve-mounting space 44 has a diameter smaller than those of the actuator-mounting space 45 and the air chamber 43. The cylinder body 41 has an annular outer surface 42 abutting against the outer cylinder 3 and formed with a plate-mounting groove 421 that extends in the axial direction (X) and that is defined by a groove bottom wall 422 and an annular surrounding wall 423. The groove bottom wall 422 of the cylinder body 41 is formed with first and second air-guiding holes 424, 425 that are spaced apart from each other in the axial direction (X) and that are communicated respectively with the valve-mounting space 44 and the air chamber 43. In this embodiment, the groove bottom wall 422 of the cylinder body 41 is curved (see FIG. 5).
Referring further to FIG. 5, the flow passage formation plate 2 is made of a rigid plastic material, is disposed between the outer cylinder 3 and the inner cylinder 4, and is mounted fixedly in the plate-mounting groove 421 by heat pressing, such as high frequency heating. In this embodiment, the flow passage formation plate 2 has a curved mounting surface 21 abutting against the groove bottom wall 422 of the cylinder body 41 of the inner cylinder 4 and formed with an axially extending groove 23 (see FIG. 4) such that the flow passage formation plate 2 cooperates with the groove bottom wall 422 of the cylinder body 41 of the inner cylinder 4 to define a flow passage (A) therebetween, as shown in FIG. 3. The flow passage (A) is in spatial communication with the first and second air-guiding holes 424, 425 in the groove bottom wall 422 of the cylinder body 41 of the inner cylinder 4. It is noted that, prior to attachment of the flow passage formation plate 2 to the inner cylinder 4, the flow passage formation plate 2 is formed integrally with an annular protrusion 24, as shown in FIG. 4. When undergoing heat pressing, the annular protrusion 24 melts. Hence, the curved mounting surface 21 is formed as described above. The flow passage formation plate 2 further has an annular outer surface 22 abutting against the annular surrounding wall 423 of the cylinder body 41 of the inner cylinder 4 so that the flow passage formation plate 2 engages fittingly the plate-mounting groove 421 in the cylinder body 41 of the inner cylinder 4.
The piston unit 6 is disposed movably and sealingly in the air chamber 43 in the inner cylinder 4, and is movable relative to the inner cylinder 4 in the axial direction (X) such that the air chamber 43 is divided into volume-changeable first and second chamber parts 431, 432. The first chamber part 431 of the air chamber 43 is in spatial communication with the valve-mounting space 44 in the inner cylinder 4. The second chamber part 432 of the air chamber 43 is in spatial communication with the second air-guiding hole 425 in the groove bottom wall 422 of the cylinder body 41 of the inner cylinder 4, as shown in FIG. 3. In this embodiment, the piston unit 6 includes a piston 61 disposed movably and sealingly in the air chamber 43 and disposed between the first and second chamber parts 431, 432, and a piston rod 62 connected fixedly to the piston 61 and extending outwardly of the second chamber part 432 of the air chamber 43 through a seal cap 5 that is mounted sealingly between the second open end 34 of the outer cylinder 3 and the inner cylinder 3.
In this embodiment, the control valve unit 7 includes a control valve 71 and an actuator 72. The control valve 71 is disposed movably and sealingly in the valve-mounting space 44. The actuator 72 is connected fixedly to the control valve 71, is disposed movably in the actuator-mounting space 45, and extends outwardly of the outer cylinder 3 via the first open end 33. The actuator 72 is operable so as to enable the control valve 71 to move between a closed position, wherein the first chamber part 431 of the air chamber 43 is not in spatial communication with the valve-mounting space 44, as shown in FIG. 3, and an opened position, where the first chamber part 431 of the air chamber 43 is in spatial communication with the valve-mounting space 44 such that the first and second chamber parts 431, 432 of the air chamber 43 are in spatial communication with each other via the first and second air-guiding holes 424, 425 in the groove bottom wall 422 of the cylinder body 41 of the inner cylinder 4 and the flow passage (A), as shown in FIG. 6.
In the present invention, the flow passage (A) can be easily formed by mounting the flow passage formation plate 2 in the plate-mounting groove 421 in the cylinder body 41 of the inner cylinder 4 through heat pressing even if the pneumatic cylinder device has a small size.
While the present invention has been described in connection with what is considered the most practical and preferred embodiment, it is understood that this invention is not limited to the disclosed embodiment but is intended to cover various arrangements included within the spirit and scope of the broadest interpretation so as to encompass all such modifications and equivalent arrangements.
Patent Application
20070290421
