Patent ID: 8784069

Claim:
A method of detecting impact between a cylinder ( 2 ) and a piston ( 1 ) driven by a linear motor, said method comprising: i) obtaining a reference signal (Sr) during a reference time interval (Δtr) before the piston attains an upper dead center position, the reference signal (Sr) varying with an electrical output of the linear motor and the reference time interval (Δtr) being defined between a first instant (t 1 ) and a second instant (t 2 ), wherein the second instant (t 2 ) occurs after the first instant (t 1 ), and the second instant (t 2 ) corresponds to the instant the piston ( 1 ) attains the upper dead center position, and obtaining a reference value (Vr) from the reference signal (Sr); ii) obtaining a detection signal (Sd) during a detection time interval (Δtd) after the piston attains the upper dead center position, the detection signal (Sd) varying with said electrical output of the linear motor and the detection time interval (Δtd) being defined between the second instant (t 2 ) and a third instant (t 3 ), wherein the third instant (t 3 ) occurs after the second instant (t 2 ), and obtaining a peak value (Vp) from the detection signal (Sd); iii) calculating a difference between the reference value (Vr) and the peak value (Vp), where the difference is compared to a pre-established tolerance value δ; and iv) recording an occurrence of impact between the cylinder ( 2 ) and the piston ( 1 ) when the result of the calculation of step iii) is higher than the pre-established tolerance value δ.