US3782844A

US3782844A - Slope control for paving machines

Info

Publication number: US3782844A
Application number: US00262949A
Authority: US
Inventors: L Burgin
Original assignee: Burgin Electronic Grade Control Inc
Current assignee: Burgin Electronic Grade Control Inc
Priority date: 1972-06-15
Filing date: 1972-06-15
Publication date: 1974-01-01
Anticipated expiration: 1991-01-01
Also published as: CA985546A

Abstract

Apparatus for sensing twisting of the screed of a paver including a pair of arms having their outer ends rigidly supported from the screed extending toward one another with their inner ends free. A gravity-type slope sensor is mounted on the inner ends of the arms to increase the sensitivity of the sensor to twisting of the screed.

Description

Jan. 1, 1974 United States Patent Burgin 44 44 NB BN M 44M44 //00 00 4444/44 00 .4 44 u 0 n es m m mw mfib ew" eb dO m a ARBPASB 0223566 5466666 9999999 WW4 WWW 6 50098 64 7 55 029 044 292 66 22 3333 B o N M I HF h Cm m m C l d m w m .10.. GM V A n .wf P E ml R .u. mmm m 1 km 1 L B E W 5 O u .m l R h 8. e T t r n u U u N L B] J m n a E 0 e P m o e m 0 W 9 6 L n s H SI A F M 5 N N 5 7 7 2 [[l 21 Appl. No.: 262,949

Primary Examiner-Nile C. Byers, Jr. Attorney-Stuart N. Senniger et al.

Related US. Application Data Continuation-impart of Ser. No. 82983, Oct. 22, 1970, abandoned.

[57] ABSTRACT Apparatus for sensing twisting of the screed of a paver including a pair of arms having their outer ends rigidly supported from the screed extending toward one another with their inner ends free. A gravity 5 BNO 49 1 type slope sensor is mounted on the inner ends of the arms to increase the sensitivity of the sens-or to twistin screed.

g of the [56] References Cited UNITED STATES PATENTS 2,491,275 12/1949 Millikin..A.......................... 404/84 13 Claims, 8 Drawing Figures PATENTEUJMI 1 m4 SHEET 1 IF 3 FIG.

PATENTEU H974 3 7-82 844 SHEET 3 BF 3 FIG. 7

SLOPE CONTROL FOR PAVING MACHINES CROSS-REFERENCE TO RELATED APPLICATION This application is a continuation-in-part of my prior copending application, U.S. Ser. No. 82,983, filed Oct. 22, 1970, now abandoned.

BACKGROUND OF THE INVENTION This invention relates to apparatus for sensing twisting of a twistable element of a machine (e.g., the screed of an asphalt paver). More particularly, this invention is concerned with apparatus for supporting a gravitytype slope sensor for amplified sensing of the twist of the screed of a paver of the like.

Generally, a conventional asphalt paver has a hopper at its front end into which hot asphaltic mix is dumped. As the paver moves forwardly over a road bed to be paved, a mix is evenly distributed on the road bed forming a mat. The surface of this mat is smoothed by a screed which is pulled along behind the paver and which floats" on the mat. The screed is conventionally an elongate, torsionally flexible member connected to the paver by pull arms having their forward ends pivoted on the paver and extending rearwardly therefrom. The grade (i.e., the inclination of the mat surface in the direction of travel of the paver) and the transverse slope (i.e., the inclination of the mat surface transversely of the direction of travel of the paver) of the mat surface are controlled by the pitch or angularity of the respective ends of the screed (referred to as angle of attack) relative to the direction of travel of the paver, and the lateral tilt of the screed. For any given angles of attack, speed of the paver and conditions of the asphaltic mix at the screed (e.g., the temperature of the mix, the consistency of the mix and the distribution of the mix in front of the leading edge of the screed), the screed will assume an equilibrium position and form the mat surface at a given grade and slope. The desired grade and slope of the mat surface may be maintained by sensing any incipient deviation in the mat surface grade and/or slope from that desired and varying the angles of attack of one or both ends of the screed to compensate for or correct such deviation.

The angle of attack of each screed end may be adjusted by rotating the respective screed end about a generally horizontal axis transverse the direction of travel such as by varying the height of the pivot connections of the forward ends of the pull arms relative to the paver as shown in U.S. Pat. No. 3,564,986 or by raising or lowering the trailing edge of each screed end relative to the leading edge thereof as illustrated in US. Pat. No. 3,029,716. These patents illustrate two different arrangements for mounting a gravity-type slope sensor on a paving machine, while another U.S. Pat. No. 2,491,275 illustrates a third arrangement wherein a slope sensor is mounted directly on the screed.

More generally, slope sensors have been mounted on pavers in three different ways, viz., on a gantry beam or the like spanning the pull or draft arms of the paver and positioned intermediate the leading and trailing ends thereof; or on a gantry beam spanning the leading ends of control arms that extend forwardly from the screed; or directly on the screed. In the first method the slope sensor will be affected by incipient slope deviations cause both by a rise or fall of one side of the forward or crawler portion of the paver moving across an irregularity in the subsurface being paved or by a change in the screed slope due to a. change in one of the many variables mentioned above that affect screed equilibrium independently of the crawlers maintaining level forward movement. However, the slope sensor in such an arrangement is relatively insensitive or only partially responsive to changes in screed equilibrium due only to changes in one of the local conditions at the screed. The second system, while sensitive to changes in screed inclination and twist due to such local conditions, is cumbersome, inconvenient and relatively expensive. The third slope sensor mounting arrangement wherein the sensor is directly mounted on the screed is also quite insensitive to screed twist due to changing local conditions at the screed.

SUMMARY OF THE INVENTION Among the several objects of this invention is the provision of apparatus for sensing the twisting of the screed of a paving machine which increases the sensi tivity of the sensor to twisting of the screed due to any cause; the provision of said apparatus which is readily. adapted for convenient mounting and use on substantially all types of paving machines; and the provision of apparatus of the class described which is of relatively simple construction, economical to fabricate and install, convenient to use and reliable in operation. Other objects and features will be in part apparent and in part pointed out hereinafter.

Briefly the apparatus of this invention comprises a pair of arms supported from a paving machine screed or the like and which extend toward one another with the outer ends rigidly connected to the screed and with their inner ends free, and means mounting a gravitytype sensor on these inner ends of the support arms to tilt it relative to the arms on tilting of either arm occasioned by twisting of the screed.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a fragmentary perspective view of the screed assembly of a conventional form of paving machine with the tilt or slope sensing device mounting apparatus of the instantinvention illustrated in operative position supporting a slope sensing control console between the pull arms and forward of the screed assembly intermediate the opposite ends of the pull arms for sensing twisting of the screed in an amplified manner and for sensing inclination of the screed;

FIG. 2 is an enlarged fragmentary vertical transverse sectional view taken substantially upon the plane indicated by the section line 2-2 of FIG. 1;

FIG. 3 is a transverse vertical sectional view taken substantially upon the plane indicated by the section line 3-3 of FIG. 2; i

FIG. 4 is a plan view of a paver showing the sensing device supported from the screed in accordance with a second embodiment of this invention;

FIG. 5 is a side elevation of the paver of FIG. 4;

FIG. 6 is an enlarged vertical section on line 6-6 of FIG. 5 with parts removed and broken away illustrating the sensor mounted on support arms rigidly connected to the ends of the screed;

FIG. 7 is a view similar to FIG. 6 showing a sensor mounted on support arms rigidly connected to the screed intermediate the outer ends of the screed in accordance with a third embodiment of this invention; and

FIG. 8 is a view similar to FIG. 6 showing the sensor tilted relative to the support arms in an amplified manner in response to twisting of the screed.

Corresponding reference characters indicate corresponding parts throughout the several views of the drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now more specifically to the drawings, the numeral 10 generally indicates a conventional form of paving machine which includes a screed assembly referred to in general by the reference numeral 12, the forward or crawler portion being illustrated partially in phantom in FIGS. 4 and 5. Screed assembly 12 includes a generally horizontal, elongate, torsionally flexible or twistable element constituted by a screed l4 and a pair of forwardly projecting pull or draft arms 16 whose rear ends are rigidly secured to opposite outer ends 54 of screed 14 and whose forward ends are pivotally anchored, as indicated at 56 (see FIGS. 4 and to the main body 58 of paving machine for oscillation about aligned horizontal transverse axes. The main body 58 of the paver has an engine for driving the paver along the road bed while towing the screed assembly therebehind.

More particularly, screed 14 includes a twistable screed plate 60 for floating on the mat of paving material deposited by the paver, the screed plate having a leading edge 62 and a trailing edge 64. A strike-off blade 66 is provided at the leading edge of the screed plate to strike off the paving material deposited in front of the screed as the paver moves forwardly. As shown in FIGS. 1 and 5, screed 14 is pivotally supported on stub beams 68 extending downwardly from the rear ends of pull arms 16 and on manually operated adjustment screws 70 carried by the pull arms. Operation of the adjustment screws causes the screed to pivot about its pivoted connection to stub beams 68 thereby enabling the angles of attack of the screed ends'to be manually adjusted. With the adjustment screws stationary, the screed is rigidly carried by the rear ends of the pull arms for movement therewith.

Paver 10 carries a grade sensor generally indicated at 72 and a gravity-type slope control console 18 for maintaining the mat surface at a predetermined grade and slope. These grade and slope controls are similar to those described in my US. Pat. No. 3,564,986. The grade control unit is usually mounted to extend outwardly from either of the pull arms 16 and is movable along a grade line string 74 or the like to sense any deviation of the selected side of the paver from the desired elevation. The angle of attack of the end of the screed on that side of the paver is then varied to compensate for such incipient deviation from the predetermined grade reference as the paver moves along. For example, as shown in FIG. 4 the grade sensor is carried by the right pull arm 16 (as viewed facing the direction of travel of the paver) and the grade sensor controls the angle of attack at the right end of the screed.

The slope control console maintains a predetermined slope of the mat surface by sensing any incipient deviations in the screed inclination or twist from the position of equilibrium existing while forming a mat surface of the desired slope, and varying the angle of attack at the other screed end to establish a new equilibrium position to compensate for this deviation and thus maintain the slope of the mat at the desired value. In the paver shown, adjustment of the angle of attack of the screed is effected by actuating hydraulic cylinder units 76 to move the forward ends of the pull arms up or down relative to the main body 58 of the paver. Each hydraulic cylinder is connected to a respective pull arm by a linkage arrangement 78, this hydraulic cylinder unit and linkage arrangement being similar to that shown in my above-mentioned US. Pat. No. 3,564,986. It will be understood that other well known means for varying the angle of attack of the screed may be utilized in place of the described hydraulic cylinder and linkage arrangement, e.g., providing power actuating means for varying independently adjustment screws 70.

In accordance with this invention, apparatus generally indicated at is provided for supporting slope sensor unit 18 from the screed 14 for tilting of the sensor in an amplified manner occasioned by twisting of the screed. In a first embodiment of apparatus 80 shown in FIGS. l-3, the control console 18 of the instant invention is mounted forwardly of screed 14 on an elongated transversely extending support or mounting platform 20, for adjustable tilting relative thereto, and the support 20 is supported for adjustable tilting from an elongated horizontal transverse tilt beam or base 22, with support 20 and base 22 together constituting a cradle generally indicated at 82 for mounting the slope sensor console 18.

A pair of arms 24 are supported from screed 14 and extend inwardly toward one another with their outer ends 24a rigidly connected to the screed via pull arms 16 and with their inner ends 24b free. Each support arm has an upstanding mounting lug or bracket 26 secured to its inner end. One end of the tilting beam 22 is pivotally supported from the upper end of one of the mounting brackets 26 by means of a pivot pin 28 and the other end of the tilting beam 22 has a pin-and-slot connection with the adjacent mounting bracket 26. The pin-and-slot connection includes a horizontal longitudinal slot 30 formed in the tilt beam 22 and a follower pin 32 secured through the upper end of that mounting bracket 26 and slidably received through the slot 30. In this manner, because the distance between the

pins

28 and 32 is only a fraction of the distance between the pull arms 16 and the support arms 24 are rigidly supported from the pull arms 16, a given degree of pivoting of the pull arms about pivots 56 relative to one another causing twisting of the screed is amplified by the tilt beam 22 and the support 20 and thus the control console 18 supported therefrom is tilted relative to support arms 24 more than the tilting which would be experienced by a horizontal transverse beam carried between the pull arms 16 centrally intermediate their opposite ends.

The central lower portion of the support 20 includes a depending mounting lug 34 pivotally supported from the upper central portion of the tilt beam 22 by means of a pivot pin 36 and in this manner the support 20 may be oscillated about an axis generally paralleling the pull arms 16 relative to tilt beam 22. A pair of adjustment screws 38 are threaded through opposite end portions of the support 20 and abut against the upper surface portions of the corresponding ends of the tilt beam 22. Thus, the screws 38 may be utilized to adjustably tilt the support 20 relative to the tilt beam 22. Still further,

latably supported from the support by means of a pivot shank 40 and one end of the control console 18 includes a pair of generally parallel arms 42 between whose adjacent sides a circular disk 44 is disposed. The

disk 44 is eccentrically mounted on a shaft 46 journalled through the support 20, and the end of the shaft 46 remote from the disk 44 includes a knob which may be manually engaged in order to rotate the shaft 46. The knob 48 includes a pointer 50 and the adjacent upstanding surface 52 of the support 20 may be provided with any suitable indicia (not shown) with which the pointer 50 may be selectively registered in order to adjustably rotate the disk 44 to predetermined adjustably rotated positions. Inasmuch as the adjacent sides of the arms 42 enjoy a light sliding contact engagement with the periphery of the disk 44, even slight rotation of the disk 44 will cause the control console 18 to be slightly pivoted or angularly adjusted relative to the support 20.

In operation, screws 38 of the apparatus of FIGS. 1-3 may be adjusted in order to level the support 20 relative to the tilt beam 22. Then, the knob 48 may be turned in order to adjustably tilt the control console 18 relative to the support 20 in the desired manner so that movement of the pull arms 16 from their predetermined relative positions may be sensed by the control console 18, this movement of the pull arms from their predetermined relative positions reflecting any twisting of the screed and indicating a change from the equilibrium position of the screed. Of course, as a change in the tilting of the pull arms 16 is sensed by the control console, a signal generated thereby effects actuation of the left hydraulic cylinder unit 76 to move the left pull arm 16 relative to the right pull arm thereby to twist the screed an appropriate amount to provide a desired equilibrium position of the screed.

Second and third embodiments of apparatus 80 of this invention are shown in FIGS. 4-6 and 8 and in FIG. 7, respectively. In both the second and third embodiments, a pair of support arms 84 are supported from the screed 14 extending toward one another with their outer ends 84a rigidly connected to the screed and with their inner ends 84b free. A cradle 86 for mounting slope sensor console 18 (this cradle being generally similar to cradle 82 heretofore described) is carried by the inner ends of the support arms for tilting of the sensor relative to the arms on tilting of either arm occasioned by twisting of the screed (see FIG. 8) thereby to sense screed twist in an amplified manner. In addition to sensing screed twist, the slope sensor also senses the inclination of the screed from one end thereof to the other. The support arms are spaced above the upper surface of screed plate 60 on mounting blocks 87 a distance sufficient to permit twisting of the screed without the support arms contacting the screed, the outer ends of the support arms being rigidly secured, as by welding, to a respective block 87 and the block being rigidly secured (welded) to the screed. The second embodiment, as shown in FIGS. 4-6 and 8, has blocks 87 secured to the upper surface of screed plate 60 adjacent its outer ends 54 with the support arms substantially in line with the leading edge 62 of the screed. In the third embodiment, as shown in FIG. 7, the blocks are secured to the screed plate intermediate its outer ends.

As shown in FIGS. 6-8, the left support arm 84 has an upwardly extending lug 88 secured to its inner end and the right support arm has a lug 90 secured to its inner end. Cradle 86 comprises a base member 92 and a mounting platform 94 with the base member connected to lugs 88 and in such manner as to permit pivoting of the cradle relative to both support arms and shifting relative to one of the support arms thereby to permit tilting of the cradle relative to the support arms. More particularly, the base member is pinned to lug 90 as indicated at 96 for pivoting relative thereto and is connected to lug 88 by means of a pin-and-slot connection, as indicated at 98, to permit both pivoting and sliding of the cradle relative to the left support arm.

Slope sensor console 18 is shown to be removably mounted on mounting platform 94 by means of springloaded quick-release latches 100 for securely holding the console on the mounting platform when latched but permitting the sensor to be readily removed therefrom. The mounting platform is pivotally carried by the base member, as indicated by the pinned connection at 102, for pivoting of the mounting platform relative to the base member about a generally horizontal axis extending parallel to the axis of pivot 96. Adjustment screws 104 threaded through the ends of the base member and engageable with the upper surface of the base member permit the inclination of the sensor to be adjusted relative to the cradle.

The second and third embodiments of apparatus 80 as shown in FIGS. 4-8 operate in substantially the same manner as the apparatus of FIGS. 1-3 to sense twisting of the screed. As shown in FIG. 8, twisting of the screed causes portions of the screed to move relative to one another. With the support arms 84 rigidly secured to the screed by blocks 87, the inner ends of the support arms reflect the relative movement of the screed at the location of the blocks. Thus, with the cradle carried by the inner ends of the support arms by the pivot and pinand-

slot connections

96 and 98, respectively, the eradle tilts relative to the support arms in an amplified manner as occasioned by twisting of the screed. Thus, amplified tilting results because the pivot and pin-andslot connections are spaced close to one another and reflect the relative movement of points on the screed (i.e., the location of blocks 87) relatively far apart from one another, thereby causing a greater amount of tilting of the cradle than if it were supported at the mounting blocks 87. Thus, a small amount of screed twist is readily sensed by the sensor carried on the cradle, and the sensitivity of the slope sensor to twisting of the screed is markedly increased.

In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.

As various changescould be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. Apparatus for sensing twisting of an elongated element, such as a screed of a paving machine or the like, which is subject to twist, said apparatus comprising a pair of arms supported from said element extending toward one another with their outer ends rigidly connected to said element and with their inner ends free, a gravity-type slope sensor, and means mounting said sensor on the inner ends of said support arms for tilting of the sensor relative to the arms on tilting of either arm occasioned by twisting of said element.

2. Apparatus as set forth in claim 1 wherein said support arms are generally in line with one another.

3. Apparatus as set forth in claim 1 wherein the outer ends of said support arms are rigidly connected to said element so as to be in substantial alignment with the leading edge thereof, said support arms being spaced above the element a distance sufficient to permit twisting of the element without the support arms contacting the element.

4. Apparatus as set forth in claim 1 wherein said support arms are located rearwardly of the leading edge of said element, said support arms being spaced above the element a distance sufficient to permit twisting of the element without the support arms contacting the element.

5. Apparatus as set forth in claim 4 wherein said support arms are located intermediate the leading and trailing edges of said element.

6. Apparatus as set forth in claim 1 wherein said support arms are located forwardly of the leading edge of said element.

7. Apparatus as set forth in claim 6 wherein said machine comprises a pair of pull arms for towing the element forwardly, the rearward end portion of each pull arm being connected to a respective outer end of said element, and wherein the outer end of each of said support arms is rigidly secured to a respective pull arm intermediate the forward end of the pull arm and the leading edge of said element thereby to support each of said support arms from the element.

8. Apparatus as set forth in claim 1 wherein said outer ends of said support arms are rigidly connected to said element adjacent its outer ends.

9. Apparatus as set forth in claim 1 wherein said outer ends of the support arms are rigidly connected to said element intermediate it outer ends.

10. Apparatus as set forth in claim 1 wherein said mounting means is pivotally connected to the inner ends of both of said support arms and is shiftable relative to one of said support arms thereby to permit tilting of the sensor relative to the support arms.

11. Apparatus as set forth in claim 10 wherein said mounting means comprises a cradle carried by the inner ends of said support arms, said cradle having means for releasably securing the sensor thereto and means for adjusting the inclination of the sensor relative to the cradle.

12. Apparatus as set forth in claim 11 wherein said cradle comprises a base member pivotally secured to the inner end of one of said support arms and secured by a sliding connection to the inner end of the other of said support arms thereby to permit pivoting of the base member relative to both of said support arms and to permit shifting of the base member relative to said other support arm when said element is twisted, and a mounting member pivotally carried by the base member for rotation about an axis extending generally parallel to the axis of said pivot connection, said means for adjusting the inclination of said sensor relative to the cradle comprising screw adjustment means for pivoting said mounting member relative to said base member.

13. Apparatus for sensing twisting of an elongate screed of a paving machine which is subject to twist, said screed extending transversely of the direction of travel of the paving machine and having its outer ends connected thereto, said apparatus comprising a pair of support arms extending inwardly of the screed toward one another substantially in line with the leading edge of the screed and with the outer ends of the support arms rigidly connected to the outer ends of the screed and with the inner end of the support arms free, said support arms being spaced above said screed a distance sufficient to permit twisting of the screed without said support arms contacting the screed, a gravity-type slope sensor, and a cradle mounting the slope sensor, said cradle being pivotally secured to the inner end of one of the support arms and secured by a pin-and-slot connection to the inner end of the other of said support arms thereby to permit tilting of the cradle and the sensor relative to the support arms on tilting of either arm occasioned by twisting of the screed.

Claims

1. Apparatus for sensing twisting of an elongate element, such as a screed of a paving machine or the like, which is subject to twist, said apparatus comprising a pair of arms supported from said element extending toward one another with their outer ends rigidly connected to said element and with their inner ends free, a gravity-type slope sensor, and means mounting said sensor on the inner ends of said support arms for tilting of the sensor relative to the arms on tilting of either arm occasioned by twisting of said element.

9. Apparatus as set forth in claim 1 wherein said outer ends of the support arms are rigidly connected to said element intermediate its outer ends.