| 摘要 |
The second cylinder (24) casing (26) includes a piston (27) with working areas (31, 32) defining fluid-filled chambers (29, 30). The third cylinder (25) casing (36) includes a piston (37) and smaller working areas (41, 42) defining fluid-filled chambers (39, 40). A valve controls fluid connection between first and second chambers. The electric motor (51) output (54) drives the moving components (10, 66) by displacing the second piston with the valve (43) open, forcing fluid from the second chamber into the first. To exert a large force on the moving components, the valve is closed and the third piston is displaced, forcing fluid from the third to the first chamber. Preferred features: The valve seats tightly, for leak-free shut-off between first and second cylinders. Second and third cylinders are mutually-integrated. The third piston is operated through a shaft by the electric motor, running in a hollow component. The second cylinder is annular with an annular piston. The third piston is slid through the annular piston by the electric motor. The third cylinder is within the second. The first piston can be moved in two opposite directions by the first hydraulic piston. The first piston is differential, as is the second; the annular chambers formed by the latter, are open to each other for flow. The third cylinder is also differential, with mutually-open chambers. A similar arrangement applies to the first cylinder. Further similar relationships are detailed. Second and third cylinders are aligned; a variant is possible, in which they are side by side. The design and its variants are further detailed in accordance with the foregoing principles. Salient features include a spring- or magnetic coupling between second and third pistons. Clutches enable selective mechanical connection of the motor to the hydraulic cylinders for mold closure and injection; the drive passing through threaded-spindle mechanisms. A belt drive is optionally included. A brake, motor or hydraulic cylinder can be employed in exerting dwell pressure. Hydraulic pressure accumulator circuits are optionally included.
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