Means and method to counterbalance the weight of a body
First Claim
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1. A mechanism to counterbalance the weight of a body, comprising:
- (a) said body being supported to pivot about a horizontal axis so that a vertical vector representing said weight of said body varies in horizontal distance from said axis during pivoting of said body thereby varying torque about said axis resulting from said weight,(b) a cam connected to said body and turning about said axis with said body during pivoting of said body about said axis,(c) a fixed anchor and a flexible member extending between and attached to said anchor and a point on said cam, said flexible member including a spring, said flexible member being disposed to wind on and off said cam as said body pivots, and(d) said cam being contoured to produce moment arms of various distances from said axis through which the force of said spring acts and producing torque equal and opposite to the torque resulting from said weight during pivoting of said body, the cam profile being defined by;
##EQU2##
space="preserve" listing-type="equation">A=θ
+C-T+EP cos T, (3)where T (tau) is the angle between the radius vector and the normal to the cam profile at successive points;
where K (kappa) is the nondimensional spring parameter;
space="preserve" listing-type="equation">K=kr.sub.o.sup.2 /T.sub.o,where k is the spring rate;
where E (epsilon) is the length ratio;
E=ro /h,where h is the distance between said horizontal axis and said fixed anchor;
where θ
is the degree of rotation;
where ro is the maximum distance of the radius vector;
where P (rho) is defined by;
space="preserve" listing-type="equation">P=r/r.sub.o,where r is the length of the radius vector at any cam angle;
where the nondimensional applied torque or moment is defined by;
space="preserve" listing-type="equation">m=T.sub.a /T.sub.o,where To is a constant with dimensions of torque dependent on a particular embodiment;
where Ta is the applied varying torque resulting from said weight pivoting about said horizontal axis;
where said radius vector extends from said horizontal axis to the point of tangency of said flexible memer and said cam profile;
where A (alpha) is the angle between said radius vector and a line from said horizontal axis to point of application of said vertical vector representing said weight of said body;
where angle C varies between π
/2 radians for generally vertical orientation of said spring force and zero radians for generally horizontal orientation of said spring force.
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Abstract
The weight of a pivoted body is counterbalanced by a spring acting on a cam connected to that body to pivot therewith. A band, connected to that spring, attaches to the cam and wraps around the cam. The cam'"'"'s profile is contoured to produce moment arms of various lengths, through which the force of the spring acts, balancing the variable torque of the weight of the pivoted body.
88 Citations
2 Claims
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1. A mechanism to counterbalance the weight of a body, comprising:
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(a) said body being supported to pivot about a horizontal axis so that a vertical vector representing said weight of said body varies in horizontal distance from said axis during pivoting of said body thereby varying torque about said axis resulting from said weight, (b) a cam connected to said body and turning about said axis with said body during pivoting of said body about said axis, (c) a fixed anchor and a flexible member extending between and attached to said anchor and a point on said cam, said flexible member including a spring, said flexible member being disposed to wind on and off said cam as said body pivots, and (d) said cam being contoured to produce moment arms of various distances from said axis through which the force of said spring acts and producing torque equal and opposite to the torque resulting from said weight during pivoting of said body, the cam profile being defined by;
##EQU2##
space="preserve" listing-type="equation">A=θ
+C-T+EP cos T, (3)where T (tau) is the angle between the radius vector and the normal to the cam profile at successive points;
where K (kappa) is the nondimensional spring parameter;
space="preserve" listing-type="equation">K=kr.sub.o.sup.2 /T.sub.o,where k is the spring rate;
where E (epsilon) is the length ratio;
E=ro /h,where h is the distance between said horizontal axis and said fixed anchor;
where θ
is the degree of rotation;
where ro is the maximum distance of the radius vector;
where P (rho) is defined by;
space="preserve" listing-type="equation">P=r/r.sub.o,where r is the length of the radius vector at any cam angle;
where the nondimensional applied torque or moment is defined by;
space="preserve" listing-type="equation">m=T.sub.a /T.sub.o,where To is a constant with dimensions of torque dependent on a particular embodiment;
where Ta is the applied varying torque resulting from said weight pivoting about said horizontal axis;
where said radius vector extends from said horizontal axis to the point of tangency of said flexible memer and said cam profile;
where A (alpha) is the angle between said radius vector and a line from said horizontal axis to point of application of said vertical vector representing said weight of said body;
where angle C varies between π
/2 radians for generally vertical orientation of said spring force and zero radians for generally horizontal orientation of said spring force.
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2. The method of counterbalancing the weight of a body, comprising:
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(a) supporting said body to pivot about a horizontal axis so that a vertical vector representing said weight of said body varies in horizontal distance from said axis during pivoting of said body thereby varying torque about said axis resulting from said weight of said body, and (b) attaching a cam to said body and attaching a flexible member to a point on said cam and wrapping said flexible member on said cam by pivoting of said body and applying a spring force to said flexible member and contouring said cam to produce moment arms of varying distances from said axis through which said spring force is caused to act and producing torque equal and opposite to the torque resulting from said weight during pivoting of said body, and defining the cam profile as follows;
##EQU3##
space="preserve" listing-type="equation">A=θ
+C-T+EP cos T, (3)where T (tau) is the angle between the radius vector and the normal to the cam profile at successive points;
where K (kappa) is the nondimensional spring constant;
space="preserve" listing-type="equation">κ
=kr.sub.o.sup.2 /T.sub.o,where k is the spring rate;
where E (epsilon) is the length ratio;
space="preserve" listing-type="equation">E=r.sub.o /h,where h is the distance between said horizontal axis and said fixed anchor;
where θ
is the degree of rotation;
where ro is the maximum distance of the radius vector;
where P (rho) is defined by;
space="preserve" listing-type="equation">P=r/r.sub.o,where r is the length of the radius vector at any cam angle;
where the nondimensional applied torque or moment is defined by;
space="preserve" listing-type="equation">m=T.sub.a /T.sub.o,where To is a constant with dimensions of torque dependent on a particular embodiment;
where Ta is the applied varying torque resulting from said weight pivoting about said horizontal axis;
where said radius vector extends from said horizontal axis to the point of tangency of said flexible member and said cam profile;
where A (alpha) is the angle between said radius vector and a line from said horizontal axis to point of application of said vertical vector representing said weight of said body;
where angle C varies between π
/2 radians for generally vertical orientation of said spring force and zero radians for generally horizontal orientation of said spring force.
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Specification
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Current AssigneeKurt O. Lund
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Original AssigneeKurt O. Lund
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InventorsLund, Kurt O.
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Primary Examiner(s)Butler, Douglas C.
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Application NumberUS07/052,113Time in Patent Office498 DaysField of Search267/172, 267/173, 267/179, 267/127, 16/1 C, 74/592, 248/572, 248/280.1, 248/292.1, 248/297.1, 248/162.1, 248/123.1, 248/289.3, 248/441.1, 248/124, 108/2, 108/4, 108/6, 108/136, 108/144, 108/146, 33/438, 33/440, 33/442, 49/386, 126/191, 126/194US Class Current267/172CPC Class CodesE05F 1/1075 for counterbalancingE05Y 2201/618 Transmission ratio variationE05Y 2201/638 Cams; RampsE05Y 2201/668 Pulleys; WheelsF16F 15/28 Counterweights, i.e. additi...Y10T 74/2158 Spring
