Shock absorber with proximity switch

• US 4,771,866 A
• Filed: 05/20/1987
• Issued: 09/20/1988
• Est. Priority Date: 04/03/1986
• Status: Expired due to Term

• Current Assignee: ACE Controls Inc. (Stabilus S.A.)
• Original Assignee: Econtrols Incorporated
• Inventors: Van Parys, Virgil J., Heideman, Robert J.
• Primary Examiner(s): Kashnikow, Andres
• Assistant Examiner(s): Oberleitner, Robert J.
• Application Number:
  US07/054,106
• Time in Patent Office: 489 Days
• Field of Search: 188/1.11, 188/281, 188/284, 188/285, 188/287, 188/299, 188/319, 248/550, 248/566, 91/1, 116/202, 116/230, 116/283, 338/32 H, 324/220, 324/207, 324/208, 92/5 R, 73/121, 340/69
• US Class Current: 188/1.11E
• CPC Class Codes: F16F 2230/08 Sensor arrangement
• CPC Class Codes: F16F 9/3207 Constructional features F16F9/34 - F16F9/50 take precedence; assembly or repair F16F9/3271
• CPC Class Codes: F16F 9/3242 of cylinder ends, e.g. caps
• CPC Class Codes: F16F 9/3292 Sensor arrangements
• CPC Class Codes: F16F 9/34 Special valve constructions F16F9/44, F16F9/50 take precedence; filtering details F16F9/3285 ; valves in general F16K; Shape or construction of throttling passages

Abstract

A shock absorber includes a piston slidably mounted in a fluid cylinder for decelerating the motion of an object acting on the shock absorber. A metering mechanism adjusts the rate at which fluid escapes from the cylinder upon displacement of the piston caused by impact of the object. A proximity sensor disposed in the end of the cylinder provides an indication of when the piston reaches a displacement position corresponding to a stroke length in which maximum energy is transferred from the object to the fluid. The proximity sensor includes an electrical probe extending through the end wall of the cylinder and possesses an electrical property whose magnitude varies in accordance with the distance between the piston and the probe.

Claims

1. A shock absorber for decelerating the movement of a moving object comprising:

(A) an outer tubular member having a central axis;

(B) an inner tubular member positioned coaxially within the outer tubular member and having an open front end;

(C) an annular rear end wall closing the rear end of said inner and outer tubular members and including a central through aperture positioned on said central axis and opening into the rear end of said inner tubular member;

(D) a piston assembly including a piston rod and a piston head, said piston rod extending into the open front end of said inner tubular member to position the rear end thereof within said inner tubular member and position the front end thereof outside of said inner tubular member for impact by the moving object, said piston head being rigid with said front end of said piston rod and slidably displaceable within said inner tubular member towards said rear end wall during a working stroke and toward the open front end of said inner tubular member during a return stroke;

(E) means defining a closed fluid loop within said shock absorber including metering orifice means;

(F) adjustment means for varying the setting of said metering orifice means and thereby varying the resistance to fluid flow through said fluid loop;

(G) a proximity sensor mounted on the rear end of said shock absorber on said rear end wall and including a main body portion positioned rearwardly of the rear exterior face of said rear end wall and a forwardly extending probe portion positioned in said central aperture in said rear end wall in communication with the interior of said inner tubular member and operative to establish a directionally electrical field extending axially forwardly into said inner tubular member from said rear end wall; and

(H) signal means operative in response to entry of the leading end of said piston assembly into said electrical field during working stroke movement of said piston head toward said rear end wall to generate a visual or audible signal indicative of such entry, whereby said shock absorber may be calibrated for a given impact loading application by adjusting said adjustment means until a signal is generated indicating arrival of said piston assembly under such given impact loading at a desired predetermined clearance distance from said rear end wall.

2. A shock absorber for decelerating the movement of a moving object comprising:

(A) an outer tubular member;

(B) an inner tubular member positioned within the outer tubular member and having an open front end and a closed rear end defined by a rear end wall of said inner tubular member;

(c) a piston assembly including a piston rod and a piston head, said piston rod extending into the open front end of said inner tubular member to position the rear end thereof within said inner tubular member and position the front end thereof outside of said inner tubular member for impact by the moving object, said piston head being rigid with said front end of said piston rod and slidably displaceable within said inner tubular member toward said rear end wall of said inner tubular member during a working stroke and toward the open front end of said inner tubular member during a return stroke;

(D) means defining a closed fluid loop within said shock absorber including metering orifice means;

(E) adjustment means for varying the setting of said metering orifice means and thereby varying the resistance to fluid flow through said fluid loop;

(F) a generally central aperture in said rear end wall;

(G) a proximity sensor mounted on the rear end of said shock absorber on said rear end wall and including a forwardly extending probe positioned in said aperture in said rear end wall in communication with the interior of said inner tubular member with the forward end of said probe spaced rearwardly from the front interior face of said rear end wall, said probe being operative to establish a directional electrical field extending axially forwardly into said inner tubular member from said rear end wall; and

(H) signal means operative in response to entry of the leading end of said piston assembly into said electrical field during working stroke movement of said piston head toward said rear end wall to generate a visual or audible signal indicative of such entry, whereby said shock absorber may be calibrated for a given impact loading application by adjusting said adjustment means until a signal is generated indicating arrival of said piston assembly under such given impact loading at a desired predetermined clearance distance from said rear end wall.

3. A shock absorber according to claim 2 wherein:

(J) said proximity sensor includes an indicator light which is normally energized but which is deenergized in response to entry of the leading end of said piston assembly into said electrical field.

4. A shock absorber according to claim 2 wherein:

(J) said proximity sensor includes a tuned oscillator which generates said electrical field and which is detuned in response to entry of the leading end of said piston assembly into said electrical field.