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Piston position drift control for free-piston device

A piston position and drift control technology, applied to reciprocating piston engines, fluid pressure actuators, engines without rotating spindles, etc., can solve the problems of small drift, difficult to effectively use sound bypass, low efficiency, etc., to achieve The effect of hyposensitivity

Inactive Publication Date: 2007-05-02
PRAXAIR TECH INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Also, acoustic bypassing is difficult to use effectively because of the actual airflow loss near the end of the tube unless the drift to be corrected is very small
Therefore, this method is generally only suitable for devices with extremely good sealing or little loss for lower efficiency

Method used

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  • Piston position drift control for free-piston device
  • Piston position drift control for free-piston device
  • Piston position drift control for free-piston device

Examples

Experimental program
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Embodiment Construction

[0019] Referring to FIG. 1 , a conventional free piston device 12 includes a reciprocating piston 14 with a seal 16 positioned adjacent to the piston 14 between interior spaces 18A and 18B. The reciprocating movement of the piston 14 is indicated by arrow A. As shown in FIG. On the free piston device 12 a pressure wave is generated in at least one interior space 18A, 18B (via structures not shown). This pressure wave creates a time-varying pressure differential across the seal 16 (ie, the time when P1 is not equal to P2 ), which can drive leaking fluid to alternately reciprocate through the seal 16 . Usually, this pressure difference is periodic and reversible. Under certain conditions, a net leak in one direction through the seal 16 may occur. For example, factors contributing to this condition may include general operating conditions, seal geometry, and the phase relationship between pressure waves and motion. The leakage of fluid tends to accumulate on one side of the pi...

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PUM

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Abstract

A piston position drift control device (110) for a free piston device (112). The control device includes a channel communicating with the internal space of the device, the channel (122) being significantly shorter than the acoustic wavelength of the device; and a check valve (124) located on the channel for controlling the In fluid communication with the interior space, the cracking pressure of said check valve is not lower than about 20% of the maximum pressure differential of the device at maximum stroke. The controls are passive, do not require active control once activated, are less susceptible to damage or contamination, and are amenable to adjustment or repair if required. In addition, the control device is small and inexpensive, and is capable of functioning over the entire working range of the free piston device it supports. An associated free piston arrangement comprising said piston position drift control arrangement is also provided.

Description

technical field [0001] This invention relates generally to piston position drift control devices for free piston devices, and more particularly to passive free piston position drift control devices employing check valves and associated free position devices. Background technique [0002] Direct conversion of alternating current (AC) power to reciprocating mechanical power by resonant motors, and inverse conversion in alternators, in small externals such as pulse tube and Stirling cycle cryocoolers and manipulated thermoacoustics or Stirling cycles Heating is becoming increasingly important in the use of engine-generators. Unlike more common rotary motors, the moving part on the device typically reciprocates along the central axis of the assembly. The movement is usually guided by means of non-contact bearings or non-friction flexures, enabling the use of non-contact and non-wearing small clearance seals between the piston and cylinder. While such seals are perfectly adequa...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): F15B11/08F01B11/00F02B77/08
CPCF02B77/08F02G2243/54F01B11/00F15B11/08
Inventor J·A·科里P·S·斯普尔
Owner PRAXAIR TECH INC