Hydraulic weighing apparatus

• US 3,992,946 A
• Filed: 12/11/1975
• Issued: 11/23/1976
• Est. Priority Date: 12/11/1975
• Status: Expired due to Term

• Current Assignee: A H Emery Company
• Original Assignee: A H Emery Company
• Inventors: Bradley, Chester D.
• Primary Examiner(s): Swisher, S. Clement
• Application Number:
  US05/639,841
• Time in Patent Office: 348 Days
• Field of Search: 73/1 B, 73/141 R, 73/406, 73/407, 73/419, 177/209, 177/208, 92/98 D
• US Class Current: 73/744
• CPC Class Codes: G01G 5/045 combined with means for totalising the pressure imposed by several load-cells

Abstract

A weighing apparatus comprises a plurality of hydraulic load cells each including a piston, a cylinder, and a flexible diaphragm of fluid impervious material sealed in the cylinder and overlying the piston to form a fluid pressure receiving chamber. The cylinders are interconnected in spaced coaxial relation on a main support frame. The pistons are similarly mounted on a floating frame which comprises a number of threaded rods which permits reciprocal piston movement relative to the cylinder and to the main frame. A force sensitive output signal generator is mounted in the main frame in operative relation to the interconnected pistons to receive forces from them when fluid pressure is received in any of the pressure receiving chambers. The pistons are adjustably clamped to the threaded by nuts so that the piston-cylinder spacing may be changed for calibration purposes. Accordingly, the amount of force exerted by any one piston on the output signal generator may be varied independently of the force exerted by any other piston. The cylinder of each load cell is formed with an undercut portion to permit the inner cylindrical wall to flex in the radial direction in response to fluid pressure received in the pressure receiving chamber to permit flexing which compensates for non-linearity of output response due to difference in acting area of the diaphragm at different relative positions of the piston and cylinder.

Claims

1. A weighing apparatus including at least one hydraulic load cell comprising:

A. a piston member,

B. cooperating cylinder means having an inner cylindrical wall for receiving said piston member in freely interfittable, relatively reciprocally movable relation, and

C. a flexible diaphragm of fluid impervious material sealed in said cylinder means and overlying said piston member to form a fluid pressure receiving chamber therebetween, an annular fold of said diaphragm interlying a portion of the free space between said cylindrical wall and said piston member,

said cylinder means having an undercut portion underlying the inner cylindrical wall to permit the inner cylindrical wall to flex in the radial direction in response to fluid pressure received in said pressure receiving chamber and said annular diaphragm fold to maintain the acting area of said diaphragm at a substantially uniform value independently of the relative position of said piston member and cylinder means.

2. A weighing apparatus as claimed in claim 1 having a plurality of hydraulic load cells and further comprising:

A. frame means for interconnecting said plurality of cylinder means in spaced coaxial relation;

B. means for interconnecting said plurality of piston members in spaced coaxial relation and permitting free reciprocal movement relative to said plurality of cylinder means and said frame means;

C. force sensitive output signal generating means mounted in said frame means in operative relation to said interconnected piston members for receiving force therefrom when fluid pressure is received in any of said pressure receiving chambers; and

D. means for adjustably varying the axial location of each piston member relative to its cooperating cylinder means

whereby the amount of force applied by each of said piston members to said output signal generating means in response to a given fluid pressure received in the respective fluid pressure receiving chamber may be equalized to calibrate said weighing apparatus.

3. The weighing apparatus as claimed in claim 2 wherein said piston member interconnecting means comprises a plurality of threaded rods mounted between said adjacent piston members.

4. The weighing apparatus as claimed in claim 3 wherein said means for adjustably varying the axial location of each piston member comprises at least one clamp nut for each piston member, threaded onto each of said threaded rods to position said piston member thereon and being rotatable to adjustably move said piston member on said rod in a direction substantially parallel to the rod axis.

5. A weighing apparatus for combining the output pressures of a plurality of hydraulic load accepting cells and for producing one output signal that is proportional to the sum of the individual load accepting cell output pressures, said weighing apparatus comprising:

A. a plurality of hydraulic load totalizer cells, each including

1. a piston member,

2. cooperating cylinder means for receiving said piston member in freely interfittable, relatively reciprocally movable relation, and

3. a flexible diaphragm of fluid impervious material sealed in said cylinder means and overlying said piston member to form a fluid pressure receiving chamber therebetween, an annular fold of said diaphragm interlying a portion of the free space between said cylinder means and said piston member, each of said hydraulic load accepting cells being in fluid communication with one hydraulic totalizer cell pressure receiving chamber,

B. frame means for interconnecting said plurality of cylinder means in spaced coaxial relation,

C. means for interconnecting said plurality of piston members in spaced coaxial relation and for permitting free reciprocal movement relative to said plurality of cylinder means and said frame means,

D. force sensitive output signal generating means mounted in said frame means in operative relation to said interconnected piston members for receiving force therefrom when fluid pressure is received in any of said pressure receiving chamber, and

E. means for adjustably varying the axial location of each piston member relative to its cooperating cylinder means

whereby the amount of force that each piston member applies to said output signal generating means in response to a given pressure received in the respective pressure receiving chamber may be equalized to calibrate said weighing apparatus.

6. The weighing apparatus as claimed in claim 5 wherein said piston member interconnecting means comprises a plurality of threaded rods mounted between adjacent piston members.

7. The weighing apparatus as claimed in claim 6 wherein said means for adjustably varying the distance between adjacent piston members comprises at least one pair of clamp nuts, for each piston member, threaded onto each of said threaded rods to clamp said piston member between said nuts, said nuts being rotatable to adjustably move said piston member on said rod in a direction substantially parallel to the piston member axis.

8. The weighing apparatus as claimed in claim 5 wherein said cylinder means comprises

A. a pressure block, and

B. a cylindrical collar member fixed to said pressure block to define a cylinder open at one end for receiving said piston member, said flexible diaphragm being sealed between said pressure block and collar member, said collar member having an undercut portion underlying the inner cylindrical surface thereof to permit the inner cylindrical wall of said collar member to flex in the radial direction in response to fluid pressure receiving chamber and said diaphragm annular fold to maintain the acting area of said diaphragm at a substantially uniform value independently of the relative position of said piston member and cylinder means.

9. A weighing apparatus for combining output pressures of a plurality of hydraulic load accepting cells and for producing one output signal that is proportional to the sum of the individual load accepting cell output pressures, said weighing apparatus comprising:

A. a plurality of hydraulic totalizer cells, each including

1. a piston member,

2. cooperating cylinder means including

a. a pressure block, and

b. a cylindrical collar member fixed to said pressure block to define a cylinder open at one end for receiving said piston member in freely interfittable, relatively reciprocally movable relation,

3. a flexible diaphragm of fluid impervious material sealed between said pressure block and collar member and overlying said piston member to form a fluid pressure receiving chamber therebetween, an annular fold of said diaphragm interlying a portion of the free space between said collar member and said piston member, said collar member having an undercut portion underlying the inner cylindrical surface thereof to permit the inner cylindrical wall of said collar member to flex in the radial direction in response to fluid pressure received in said pressure receiving chamber and said diaphragm annular fold to maintain the acting area of said diaphragm at a substantially uniform value independently of the relative position of said piston member and cylinder means, each of said hydraulic load accepting cells being in fluid communication with one hydraulic totalizer cell pressure receiving chamber,

B. frame means for interconnecting said plurality of cylinder means in spaced coaxial relation,

C. means for interconnecting said plurality of piston members in spaced coaxial relation and for permitting free reciprocal movement relative to said plurality of cylinder means and said frame means,

D. force sensitive output signal generating means mounted in said frame means in operative relation to said interconnected piston members for receiving forces therefrom when fluid pressure is received in any of said pressure receiving chambers, and

E. means for adjustably varying the axial location of each piston member relative to its cooperating cylinder means

whereby the amount of force applied to said output signal generating means by each piston member in response to a given fluid pressure received in the respective pressure receiving chamber may be equalized to calibrate said weighing apparatus.

10. In a hydraulic load measuring device for combining the output pressures of a plurality of hydraulic load accepting cells for producing one output signal that is proportional to the sum of the individual load accepting cell output pressures, and having a plurality of vertically arranged hydraulic totalizer load cells each including a cylinder, a cooperating piston reciprocally carried in each cylinder and a diaphragm enclosing each cylinder and overlying the associated piston to define a variable volume fluid pressure receiving chamber therebetween, a frame interconnecting and mounting said cylinders in vertically spaced relation, and force sensitive output signal generating means mounted in said frame;

an apparatus for calibrating said hydraulic load totalizer to have the same output for the same input to each individual hydraulic load accepting cell, said calibrating apparatus comprising;

A. means for interconnecting the plurality of pistons in spaced vertical relation with one of the pistons in operative relation to the force sensitive output signal generating means for applying pressure thereto when fluid pressure is received in any of the hydraulic totalizer cell pressure receiving chambers, and

B. means for adjustably varying the axial location of each piston relative to its cooperating cylinder

whereby the amount of force applied to the output signal generating means by each piston in response to a given fluid pressure received in the respective hydraulic totalizer cell pressure receiving chamber may be equalized to calibrate said load measuring device.