Automatic crowning system for pavers

Claim 2

In a paving machine comprising a surface template and crown control means to effect a crown adjustment of said template by varying the spacing of intermediate points thereof with respect to a lateral plane passing through the end points thereof, the improvement which comprises a. reversible motor means for operating said crown control means in either direction, to increase or decrease the crown contour of the template, b. sensing means responsive in part to an external crown reference datum and responsive in part to the magnitude of crown adjustment in said template, and c. control circuit means functionally effective to compare the responses of said sensing means and to energize said motor means in response thereto.

Claim 3

A paving machine according to claim 1, further characterized by a. said sensing mans comprising a sensing element and a support therefor carried by said template, b. said sensing element being movable relative to its support in response to changes in said reference datum relative to the template, c. said support being movable relative to the reference datum in response to changes in the crown adjustment of said template, to effect a null of the sensing element response.

Claim 4

A paving machine according to claim 2, further characterized by a. a support carried by the template at one side and extending laterally outward beyond the outer edge of said template, b. said sensing means comprising a sensing element carried by said support and movable thereby relative to said lateral plane in opposite relation to crown adjusting movements of intermediate portions of said template.

Claim 5

A paving machine according to claim 1, further characterized by a. said sensing means comprising first and second sensing elements, b. the first sensing element being responsive to the external reference datum, c. the second sensing element being responsive to the magnitude of crown adjustment in said template, and d. said control circuit means being operative to energize said motor in a direction to move said second sensing element toward a null relation with respect to said first sensing element.

Claim 6

The invention of claim 1 wherein: a. the surface template comprises a bottom plate secured at its sides to side support members, b. said crown adjusting means comprises means to raise and lower the midpoint of said plate with respect to the plate sides, c. said external reference datum comprises a reference structure extending along a side of the path followed by the paving machine, d. said sensing means includes a sensing element in registry with the reference structure and mounted for movement with one side support member responsive to vertical crowning adjusting of the bottom plate, e. the control means actuating the crown adjustment means in response to the sensing element detecting change in elevation of the reference structure, and f. the adjusting means operating to vertically adjust the midpoint of the template in a direction to pivot the sensing element and restore its position relative to the reference structure.

Claim 7

The invention of claim 1 wherein: a. the template comprises a bottom plate with its midpoint adapted to be elevated and depressed relative to its side edges, b. the crown adjusting means operates to elevate and depress the template midpoint relative to said lateral plane, c. the control circuit means including circuit means generating control signals responsive to the reference datum indicating a crown change, d. the control signals actuating the adjusting means to change template midpoint elevation relative to said lateral plane in a direction corresponding to reference datum change, and e. a feedback circuit to balance said control signals responsive to the indicated respective elevation or depression of the template midpoint.

Claim 8

The invention of claim 6 wherein a. the reference datum comprises a reference structure extending along the roadway course and varying in elevation in accordance with a predetermined crowning program, b. said control circuit including a sensing element detecting variation in reference structure elevation to generate said control signals, and c. said feedback signals incLuding a second sensing element sensing elevation or depression of the template to generate feedback signals which balance the control signals.

Claim 9

The invention of claim 7 wherein a. the second sensing element is mounted for movement with the template at a position between its side edges, b. the element being biased against the main frame to detect relative movement between the frame and template midpoint to generate said control signals.

Claim 10

The invention of claim 6 wherein a. the crown adjusting means includes a motor to vary template midpoint elevation, and b. said control signals operate to actuate said motor to elevate or depress said midpoint relative to said lateral plane until the feedback signals balance said control signals.

Claim 11

The invention of claim 1 wherein a. the template comprises a bottom plate articulated at its midpoint and mounted to the main frame at respective sides thereof, and b. the adjusting means comprising an actuator connected between the frame and said articulated midpoint to elevate and depress said midpoint relative to said lateral plane for changing the crown.

Claim 12

The invention of claim 10 wherein a. the control means includes a crowning sensor mounted on said frame and extending in registry with said reference datum, b. said sensor generating control signals to operate the actuator in response to a crowning change reflected in the reference datum, and c. feedback sensor means generating feedback signals to balance said control signals in response to elevation or depression of intermediate points of the template relative to said lateral plane for adjusting template profile to a position corresponding to said changed reference datum.

Claim 13

The invention of claim 10 wherein a. the control means includes a support arm pivotally mounted to the frame, b. a crowning sensor element mounted on one end of the support arm and positioned in registry with said reference datum to generate control signals for operating the adjusting means in response to crowning changes in the reference datum, and c. feedback linkage means connected between the template and the support arm to pivot said support arm for cancelling said control signals responsive to indicated elevation or depression of intermediate portions of the template relative to said lateral plane.

Claim 16

The method of claim 13 wherein a. the step of generating the control signals comprises producing first and second electrical signals responsive to datum changes of respective increasing or decreasing crown change, and b. increasing or decreasing the elevation of the template midpoint, with respect to a lateral plane between its edges, in response to respective first or second signals.

Claim 17

The method of claim 14 wherein a. the step of terminating crown adjustment comprises producing first and second electrical feedback signals responsive to respective elevation or depression of the template midpoint with respect to said lateral plane, and b. balancing the first and second control signals by first and second feedback signals equal in magnitude thereto.