US 12,092,135 B2
Constant value method for detecting and evaluating internal leakage of hydraulic cylinder and detection device thereof
Bing Xu, Hangzhou (CN); Xuguang Li, Hangzhou (CN); Junhui Zhang, Hangzhou (CN); Huaizhi Zong, Hangzhou (CN); Xinlei Xu, Hangzhou (CN); and Weidi Huang, Hangzhou (CN)
Assigned to ZHEJIANG UNIVERSITY, Hangzhou (CN)
Filed by ZHEJIANG UNIVERSITY, Zhejiang (CN)
Filed on Jan. 9, 2024, as Appl. No. 18/408,440.
Application 18/408,440 is a continuation of application No. PCT/CN2022/136676, filed on Dec. 5, 2022.
Claims priority of application No. 202210115151.6 (CN), filed on Feb. 4, 2022.
Prior Publication US 2024/0141931 A1, May 2, 2024
Int. Cl. F15B 19/00 (2006.01); F15B 13/04 (2006.01); G01M 3/32 (2006.01)
CPC F15B 19/005 (2013.01) [F15B 13/0401 (2013.01); G01M 3/3236 (2013.01)] 8 Claims
OG exemplary drawing
 
1. A constant value method for detecting and evaluating an internal leakage in a hydraulic cylinder, comprising:
step (1), measuring a pressure drop value Δp of the internal leakage of the hydraulic cylinder Δp represents a pressure drop value of a high-pressure chamber caused by the internal leakage of the hydraulic cylinder, comprising:
step (1.1), measuring a first pressure drop Δp-1 of a reference chamber, comprising:
supplying oil to the reference chamber;
when a pressure of the reference chamber reaches a rated test pressure, allowing the reference chamber to be in a pressure-maintaining state of the reference chamber, wherein a first pressure of the reference chamber is p1-1 at this moment, and wherein after maintaining the pressure of the reference chamber for a predetermined time, a second pressure of the reference chamber is p2-1; and
obtaining a difference between p1-1 and p2-1 as the pressure drop Δp-1 of the reference chamber;
step (1.2), measuring a pressure drop Δp-2 of the hydraulic cylinder, comprising:
disassembling the reference chamber in the step (1.1) by a pipeline disassembly joint, and assembling the hydraulic cylinder on a same hydraulic test bench;
supplying oil to the high-pressure chamber of the hydraulic cylinder, and driving the hydraulic cylinder to extend to an end of a stroke;
when a pressure of the hydraulic cylinder reaches the rated test pressure, allowing the hydraulic cylinder to be in a pressure-maintaining state of the hydraulic cylinder, wherein a first pressure of the high-pressure chamber of the hydraulic cylinder is p1-2 at this moment, and wherein after maintaining the pressure of the high-pressure chamber of the hydraulic cylinder for the predetermined time, a second pressure of the high-pressure chamber of the hydraulic cylinder is p2-2; and
obtaining a difference between p1-2 and p2-2 as a second pressure drop Δp-2 of the hydraulic cylinder; and
step (1.3), calculating an accurate pressure drop value Δp of the internal leakage in the hydraulic cylinder: the accurate pressure drop value Δp of the internal leakage in the hydraulic cylinder is Δp=Δp-2-Δp-1;
step (2), determining whether the hydraulic cylinder satisfies a standard:
when a product of the pressure drop value Δp of the internal leakage of the hydraulic cylinder and a hydraulic stroke L corresponding to the pressure drop value Δp, namely Δp×L, is less than a standard parameter C for evaluating the internal leakage of the hydraulic cylinder, that is, Δp×L<C, wherein,

OG Complex Work Unit Math
where Q is a standard value of the internal leakage of the hydraulic cylinder defined as

OG Complex Work Unit Math
wherein K is an elastic modulus of an oil in the cylinder, t is a test time for measuring the internal leakage of the hydraulic cylinder, L is the stroke of the hydraulic cylinder and D is an inner diameter of the hydraulic cylinder, the internal leakage of the hydraulic cylinder satisfies the standard; and
 when Δp×L≥C, the internal leakage of the hydraulic cylinder does not satisfy the standard.