Controller for a paving screed heating system

(54) CONTROLLER FOR A PAVING SCREED HEATING SYSTEM

(75) Inventors: Timothy D. Williams, Charleston;

Michael J. Worley, Mattoon, both ol
IL (US); Brian V. Thompson,

Headington (GB)

(73) Assignee: Blaw Knox Construction Equipment Corporation, Mattoon, IL (US)

( * ) Notice: Subject to any disclaimer, the term of this patent is extended or adjusted under 35 U.S.C. 154(b) by 0 days.

(21) Appl. No.: 09/502,964

(22) Filed: Feb. 11, 2000

Related U.S. Application Data

(60) Provisional application No. 60/119,708, filed on Feb. 11, 1999.

(51) Int. CI.7 E01C 23/07; E01C 23/14

(52) U.S. CI 404/79; 404/84.05; 404/95;

700/19; 700/300

(58) Field of Search 404/75, 79, 84.05,

404/95, 118; 700/2, 19, 20, 207, 299, 300

(56) References Cited

U.S. PATENT DOCUMENTS

3,557,672 A 1/1971 Shurtz et al.

4,319,856 A * 3/1982 Jeppson 404/79

4,409,662 A * 10/1983 Rao 700/300

4,429,216 A 1/1984 Brigham

4,561,800 A * 12/1985 Hatakenaka et al 404/79

4,656,339 A 4/1987 Grise

4,661,689 A 4/1987 Harrison

4,717,812 A 1/1988 Makita

4,725,717 A 2/1988 Harrison

4,752,155 A 6/1988 Rennich

4,942,078 A 7/1990 Newman et al.

A controller is for a heating system of a paving screed including a screed plate. The heating system is connected with the screed and configured to transfer thermal energy to the screed plate and includes an actuator configured to adjust thermal energy output of the heating system. The controller includes a temperature sensor connectable with the screed and configured to sense temperature of the screed plate. The sensor is also configured to generate electrical signals proportional to sensed temperature. An electrical logic circuit is electrically connected with the sensor and is electrically connectable with the actuator. The logic circuit is configured to compare a temperature signal from the sensor with a desired temperature value and to automatically operate the actuator such that the actuator adjusts thermal energy output of the heating system so as to maintain screed temperature about the desired temperature value. The logic circuit is a microprocessor and the temperature sensor is preferably a thermocouple. The microprocessor has a stored software program that selectively configures the heating system for use with various types of screed heaters.

6 Claims, 2 Drawing Sheets

1

CONTROLLER FOR A PAVING SCREED
HEATING SYSTEM

This application claims the benefit of U.S. Provisional Application No. 60/119,708, filed Feb. 11, 1999.

BACKGROUND OF THE INVENTION

The present invention relates to paving screeds, and more particularly to controllers used with systems for heating paving screeds.

The quality of an asphalt mat is affected by the temperature of the asphalt material during the paving process. One method for ensuring that the asphalt is at a sufficiently high temperature is to use a heated screed, such that thermal energy (i.e., heat) is transferred from the screed to the asphalt while the material is being leveled by the screed. Systems for heating a paving screed include one or more heaters located inside the housing of the screed and configured to transfer thermal energy to the screed plate (the portion of the screed that actually levels the asphalt). Such heating systems include gas burners, usually for diesel or propane gas, in combination with "blower" fans, electrical resistance heaters, etc.

In general, the control of such screed heating systems is merely a simple "on-off" switch that requires the screed operator to start the heating system and then the system operates until such time as the operator decides to shut the system off. If the operator does not properly monitor the temperature of the screed, excessive heating of the screed, causing poor asphalt mat finish or damage to the screed components. Further, if the screed operator shuts down the heating system and then forgets to re-start system, the quality of the asphalt mat is diminished due to leveling with a "cold" screed.

Therefore, it would be desirable to have a controller for a paving screed heating system that operates safely and ensures that the heating system does not over-heat or insufficiently heat the screed.

SUMMARY OF THE INVENTION

The present invention is controller for a heating system of a paving screed including a screed plate. The heating system is connected with the screed and is configured to transfer thermal energy to the screed plate. The heating system 1 further includes an actuator 16 configured to adjust thermal energy output of the heating system. The controller comprises a temperature sensor connectable with the screed and configured to sense temperature of the screed plate. The sensor is also configured to generate electrical signals proportional to sensed temperature. Further, an electrical logic circuit is electrically connected with the sensor and electrically connectable with the actuator. The logic circuit is configured to compare a temperature signal from the sensor with a desired temperature value and to automatically operate the actuator such that the actuator adjusts thermal energy output of the heating system so as to maintain the screed temperature about the desired temperature value.

BRIEF DESCRIPTION OF THE SEVERAL
VIEWS OF THE DRAWINGS

The description of the invention below will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, there is shown in the drawings, which are diagrammatic, embodiments that are presently preferred. It should be understood,

2

however, that the invention is not limited to the precise arrangements and instrumentalities shown. In the drawings: FIG. 1 is a schematic diagram of the control system in accordance with the present invention; and 5 FIG. 2 is a front plan view of the controller console of the present invention.

DESCRIPTION OF THE INVENTION

Referring now to the drawings in detail, wherein like numbers are used to indicate like elements throughout, there is shown in FIGS. 1-2 a presently preferred control system 10 for a heating system 1 for a paving screed 2. The screed 2 includes a least one screed plate 3 used to level paving material (e.g., asphalt) and the heating system 1 is connected with the screed plate 3 and configured to transfer thermal energy to the plate 3. The heating system 1 further includes an actuator 16 configured to adjust thermal energy output of the heating system 1.

2Q The control system 10 basically comprises a temperature sensor 12 connectable with the screed 2 and configured to sense temperature of the screed plate 3 and to generate electrical signals proportional to sensed temperature. An electrical logic circuit 14 is electrically connected with the

25 sensor 12 and is electrically connectable with the actuator 16. The logic circuit 14 is configured to compare a temperature signal from the sensor 12 with a desired temperature value and to automatically operate the actuator 16 such that the actuator 16 adjusts thermal energy output of the heating

3Q system 1 so as to maintain screed temperature about the desired temperature value.

More specifically, the temperature sensor 12 measures the temperature of the screed plate 3 and transmits electrical signals corresponding to the measured temperature to the

35 logic circuit 14. The electrical logic circuit 14 is connected with the sensor 12 and is configured to receive signals corresponding to the temperature measurements taken by the sensor 12. The logic circuit compares measured temperature of the screed 1 with a desired temperature or with a values

4q of a temperature range (the "temperature band"). If the measured temperature is above a desired temperature or above a maximum temperature of the temperature range, the logic circuit 14 sends a first control signal to the actuator 16 such that the heating system 4 is either "shut off" or the

45 thermal output of the heating system 1 is reduced. Further, the logic circuit 14 is also configured to transmit a second control signal to the actuator 16 when the measured temperature is below either a desired temperature or a minimum value in the temperature range, such that the actuator 16

5q either "turns on" the heating system 1 or increases the thermal output of the heating system 1. Each of the above elements is discussed in further detail below.

The temperature sensor 12 is preferably a thermocouple, and most preferably a plurality of thermocouples disposed

55 proximal to the screed plate 3 and attached thereto. As thermocouples are well known, a detailed description is not necessary for the purposes of the present disclosure. Alternatively, the temperature sensor 12 may be any other type of device for measuring temperature that is capable of

60 communicating or interacting with a electric logic circuit 14. It is within the scope of the present invention to utilize any appropriate device for the temperature sensor 12 that is capable of measuring the temperature of the screed plate 3 and transmitting information corresponding to the tempera

65 ture to the logic circuit 14.

The logic circuit 14 is preferably a microprocessor 18 having programmable electronic memory, in other words,