U.S. patent application number 13/236442 was filed with the patent office on 2012-01-12 for method and system for calculating and reporting slump in delivery vehicles.
This patent application is currently assigned to VERIFI LLC. Invention is credited to Jerold Brickler, John I. Compton, Roy Cooley, Robert B. Fitzpatrick, Mark E. Peters, Michael Topputo, Steve Verdino.
Application Number | 20120008453 13/236442 |
Document ID | / |
Family ID | 40136337 |
Filed Date | 2012-01-12 |
United States Patent
Application |
20120008453 |
Kind Code |
A1 |
Cooley; Roy ; et
al. |
January 12, 2012 |
Method and System for Calculating and Reporting Slump in Delivery
Vehicles
Abstract
A system for managing a concrete delivery vehicle having a
mixing drum 14 and hydraulic drive 16 for rotating the mixing drum,
including a rotational sensor 20 configured to sense a rotational
speed of the mixing drum, a hydraulic sensor 22 coupled to the
hydraulic drive and configured to sense a hydraulic pressure
required to turn the mixing drum, a temperature sensor for sensing
temperature of the drum, and a communications port 26 configured to
communicate a slump calculation to a status system 28 commonly used
in the concrete industry, wherein the sensing of the rotational
speed of the mixing drum is used to qualify a calculation of
current slump based on the hydraulic pressure required to turn the
mixing drum. Temperature readings are further used to qualify or
evaluate a load. Also, water purge connections facilitate cold
weather operation.
Inventors: |
Cooley; Roy; (West Chester,
OH) ; Compton; John I.; (Lexington, KY) ;
Topputo; Michael; (Hamilton, OH) ; Verdino;
Steve; (Hamilton, OH) ; Brickler; Jerold;
(Liberty Township, OH) ; Fitzpatrick; Robert B.;
(Cincinnati, OH) ; Peters; Mark E.; (Hamilton,
OH) |
Assignee: |
VERIFI LLC
West Chester
OH
|
Family ID: |
40136337 |
Appl. No.: |
13/236442 |
Filed: |
September 19, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11764832 |
Jun 19, 2007 |
8020431 |
|
|
13236442 |
|
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Current U.S.
Class: |
366/10 |
Current CPC
Class: |
B28C 7/022 20130101;
B28C 7/026 20130101; B28C 5/4275 20130101; B28C 5/4231 20130101;
B28C 5/422 20130101 |
Class at
Publication: |
366/10 |
International
Class: |
B28C 7/12 20060101
B28C007/12 |
Claims
1. A system for managing a concrete delivery vehicle having a
mixing drum and a water supply for use therewith, and water
connections for delivery of water from said water supply,
comprising: air connections coupling an air supply to said water
connections, control valves in one or both of said air and water
connections, and a controller controlling said control valves to
deliver air through said water connections and purge water from
said water connections to prevent freezing of water within said
water connections.
2. The system of claim 1 wherein said air connections deliver air
to said water connections to purge water from said water
connections into said water supply.
3. The system of claim 1 wherein said air connections deliver air
to said water connections to purge water from said water
connections into said mixing drum.
4. The system of claim 1 wherein said concrete delivery vehicle
further comprises a chemical additive supply and chemical additive
connections for delivery of chemical additive from said chemical
additive supply, the system further comprising air connections
coupling said air supply to said chemical additive connections,
said control valves being in any or all of said air, water and
chemical additive connections, the controller controlling said
control valves to purge chemical additive and water from said
connections.
5. The system of claim 2 further comprising a pump coupled to said
water connections, said controller controlling said pump to purge
water from said water connections.
6. The system of claim 2 wherein said vehicle comprises a primary
and a secondary air supply, and air connections delivering air from
said primary and secondary air supplies to said water connections,
the controller controlling the secondary air supply to purge water
from said water connections into said water supply while said water
supply is pressurized by said primary air supply.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is divisional of U.S. application Ser. No.
11/764,832 filed Jun. 19, 2007, which is related to pending U.S.
application Ser. No. 10/599,130, which was filed Feb. 14, 2005 as a
PCT Application designating the United States claiming priority to
U.S. Provisional Application 60/554,720, and which subsequently
entered the U.S. National Phase and is now pending, which
applications are hereby incorporated by reference.
FIELD OF THE INVENTION
[0002] The present invention generally relates to delivery vehicles
and particularly to mobile concrete mixing trucks that mix and
deliver concrete. More specifically, the present invention relates
to the calculation and reporting of slump using sensors associated
with a concrete truck.
BACKGROUND OF THE INVENTION
[0003] Hitherto it has been known to use mobile concrete mixing
trucks to mix concrete and to deliver that concrete to a site where
the concrete may be required. Generally, the particulate concrete
ingredients are loaded at a central depot. A certain amount of
liquid component may be added at the central depot. Generally the
majority of the liquid component is added at the central depot, but
the amount of liquid is often adjusted. The adjustment is often
unscientific, the driver adds water from any available water supply
(sometimes there is water on the truck) by feeding a hose directly
into the mixing barrel and guessing as to the water required.
Operators attempt to tell by experience the correct or approximate
volume of water to be added according to the volume of the
particulate concrete ingredients. The adding of the correct amount
of liquid component is therefore usually not precise.
[0004] It is known that if concrete is mixed with excess liquid
component, the resulting concrete mix does not dry with the
required structural strength. At the same time, concrete workers
tend to prefer more water, since it makes concrete easier to work.
Accordingly, slump tests have been devised so that a sample of the
concrete mix can be tested with a slump test prior to actual usage
on site. Thus, if a concrete mixing truck should deliver a concrete
mix to a site, and the mix fails a slump test because it does not
have sufficient liquid component, extra liquid component may be
added into the mixing barrel of the concrete mixing truck to
produce a required slump in a test sample prior to actual delivery
of the full contents of the mixing barrel. However, if excess water
is added, causing the mix to fail the slump test, the problem is
more difficult to solve, because it is then necessary for the
concrete mixing truck to return to the depot in order to add extra
particulate concrete ingredients to correct the problem. If the
extra particulate ingredients are not added within a relatively
short time period after excessive liquid component has been added,
then the mix will still not dry with the required strength.
[0005] In addition, if excess liquid component has been added, the
customer cannot be charged an extra amount for return of the
concrete mixing track to the central depot for adding additional
particulate concrete ingredients to correct the problem. This, in
turn, means that the concrete supply company is not producing
concrete economically.
[0006] One method and apparatus for mixing concrete in a concrete
mixing device to a specified slump is disclosed by Zandberg et al.
in U.S. Pat. No. 5,713,663 (the '663 patent), the disclosure of
which is hereby incorporated herein by reference. This method and
apparatus recognizes that the actual driving force to rotate a
mixing barrel filled with particulate concrete ingredients and a
liquid component is related to the volume of the liquid component
added. In other words, the slump of the mix in the barrel at that
time is related to the driving force required to rotate the mixing
barrel. Thus, the method and apparatus monitors the torque loading
on the driving means used to rotate the mixing barrel so that the
mix may be optimized by adding a sufficient volume of liquid
component in attempt to approach a predetermined minimum torque
loading related to the amount of the particulate ingredients in the
mixing barrel.
[0007] More specifically, sensors are used to determine the torque
loading. The magnitude of the torque sensed may then be monitored
and the results stored in a storage means. The storage means can
subsequently be accessed to retrieve information therefrom which
can be used, in turn, to provide processing of information relating
to the mix. In one case, it may be used to provide a report
concerning the mixing.
[0008] Improvements related to sensing and determining slump are
desirable.
[0009] Other methods and systems for remotely monitoring sensor
data in delivery vehicles are disclosed by Buckelew et al. in U.S.
Pat. No. 6,484,079 (the '079 patent), the disclosure of which is
also hereby incorporated herein by reference. These systems and
methods remotely monitor and report sensor data associated with a
delivery vehicle. More specifically, the data is collected and
recorded at the delivery vehicle thus minimizing the bandwidth and
transmission costs associated with transmitting data back to a
dispatch center. The '079 patent enables the dispatch center to
maintain a current record of the status of the delivery by
monitoring the delivery data at the delivery vehicle to determine
whether a transmission event has occurred. The transmission events
are defined by the dispatch center to include those events that
mark delivery progress. When a transmission event occurs, the
sensor data and certain event data associated with the transmission
event may be transmitted to the dispatch center. This enables the
dispatch center to monitor the progress and the status of the
delivery without being overwhelmed by unnecessary information. The
'079 patent also enables data concerning the delivery vehicle and
the materials being transported to be automatically monitored and
recorded such that an accurate record is maintained for all
activity that occurs during transport and delivery.
[0010] The '079 patent remotely gathers sensor data from delivery
vehicles at a dispatch center using a highly dedicated
communications device mounted on the vehicle. Such a communications
device is not always compatible with status systems used in the
concrete industry.
[0011] Improvements related to monitoring sensor data in delivery
vehicles using industry standard status systems are desirable.
[0012] A further difficulty has arisen with the operation of
concrete delivery vehicles in cold weather conditions. Typically a
concrete delivery truck carries a water supply for maintaining the
proper concrete slump during the delivery cycle. Unfortunately this
water supply is susceptible to freezing in cold weather, and/or the
water lines of the concrete truck are susceptible to freezing. The
truck operator's duties should include monitoring the weather and
ensuring that water supplies do not freeze; however, this is often
not done and concrete trucks are damaged by frozen pipes, and/or
are taken out of service to be thawed after freezing.
[0013] Accordingly, improvements are needed in cold weather
management of concrete delivery vehicles.
[0014] Published PCT Application PCT/US2005/004405, filed by the
assignee of the present application, discloses an improved concrete
truck management and slump measurement system that addresses many
of the above needs; however, further improvement in management and
delivery of concrete is advantageous.
SUMMARY OF THE INVENTION
[0015] In one aspect, the present invention comprises a system for
managing a mixing drum that includes a temperature sensor mounted
to the drum and configured to sense a temperature of the drum
and/or its contents, and wirelessly transmit this information from
the sensor to a receiver coupled to a processor that may use the
temperature information in evaluating the contents of the drum.
[0016] The use of a temperature sensor permits new and important
features. For example, the quality of a concrete mixture may be
assessed by its temperature, or temperature history, particularly,
but not limited to, where the temperature probe extends into direct
contact with the contents of the drum, for example by reference to
a stored curve that can be particular to the mix that is placed in
the drum. This process may be made more accurate by the use of a
second temperature sensor reading the drum temperature separately
from the contents.
[0017] In a second aspect, the invention features an accelerometer
sensor mounted to the delivery truck for detecting tilt angle,
acceleration or deceleration, or engine status of the vehicle.
[0018] This aspect permits computation of, e.g., concrete slump,
and other mixing factors or variables, accounting for tilt angle of
the truck and/or acceleration and deceleration of the truck, which
can affect hydraulic pressure, and torque of the drum drive
system.
[0019] In a third aspect, the invention further features a
communication system for sharing information with multiple
locations, so that a delivery truck operating in accordance with
the invention may, e.g., receive a software update at a plant
facility and then deliver that update to another truck in the
field. Alternately, a truck in the field may receive status
information from another truck in the field and then deliver that
status information to the plant.
[0020] According to another aspect of the invention, concrete slump
calculations are enhanced by the use of stored curves or models of
slump vs. other measured variables. A family of such curves can be
used to adjust for differences in concrete mixture, or other
variables such as temperature, aggregate type, and the like.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] FIG. 1 is block diagram of a system for calculating and
reporting slump in a delivery vehicle constructed in accordance
with an embodiment of the invention;
[0022] FIG. 2 is a flow chart generally illustrating the
interaction of the ready slump processor and status system of FIG.
1;
[0023] FIG. 3 is a flow chart showing an automatic mode for the RSP
in FIG. 1;
[0024] FIG. 4 is a flow chart of the detailed operation of the
ready slump processor of FIG. 1;
[0025] FIG. 4A is a flow chart of the management of the horn
operation by the ready slump processor;
[0026] FIG. 4B is a flow chart of the management of the water
delivery system by the ready slump processor;
[0027] FIG. 4C is a flow chart of the management of slump
calculations by the ready slump processor;
[0028] FIG. 4D is a flow chart of the drum management performed by
the ready slump processor;
[0029] FIG. 5 is a state diagram showing the states of the status
system and ready slump processor;
[0030] FIGS. 6A, 6B, 6C, 6D, 6E and 6F illustrate the six types
water evacuation systems for cold weather operation;
[0031] FIG. 7 is a side view of a concrete mixing truck to
illustrate the location of the access door on the side of the
mixing drum;
[0032] FIG. 8 is an exploded view of the dual temperature
sensor;
[0033] FIG. 9 is an illustration of the relationship between
hydraulic mix pressure and slump; and
[0034] FIG. 10 is an illustration of the relationship of the Energy
Release Rate to the relative time for concrete to go through a
hydration process as it pertains to mix composition.
DETAILED DESCRIPTION OF THE EMBODIMENTS OF THE INVENTION
[0035] Referring to FIG. 1, a block diagram of a system 10 for
calculating and reporting slump in a delivery vehicle 12 is
illustrated. Delivery vehicle 12 includes a mixing drum 14 for
mixing concrete having a slump and a motor or hydraulic drive 16
for rotating the mixing drum 14 in the charging and discharging
directions, as indicated by double arrow 18. System 10 comprises a
dual temperature sensor 17, which may be installed directly to on
the mixing drum 14, more specifically the access door of the mixing
drum 14, and configured to sense both the load temperature as well
as the skin temperature of the mixing drum 14. The dual temperature
sensor 17 may be coupled to a wireless transmitter. A wireless
receiver mounted to the truck could capture the transmitted signal
from the dual temperature sensor 17 and determine the temperature
of both the load and the mixing drum skin. System 10 further
includes an acceleration/deceleration/tilt sensor 19, which may be
installed on the truck itself, and configured to sense the relative
acceleration, deceleration of the truck as well as the degree of
tilt that the truck may or may not be experiencing. System 10
comprises a rotational sensor 20, which may be installed directly
on or mounted to the mixing drum 14, or included in the motor
driving the drum, and configured to sense the rotational speed and
direction of the mixing drum 14. The rotational sensor may include
a series of magnets mounted on the drum and positioned to interact
with a magnetic sensor on the truck to create a pulse each time the
magnet passes the magnetic sensor. Alternatively, the rotational
sensor may be incorporated in the driving motor 16, as is the case
in concrete trucks using Eaton, Rexroth, or other hydraulic motors
and pumps. In a third potential embodiment, the rotational sensor
may be an integrated accelerometer mounted on the drum of the
concrete truck, coupled to a wireless transmitter. In such an
embodiment a wireless receiver mounted to the truck could capture
the transmitted signal from the accelerometer and determine
therefrom the rotational state of the drum. System 10 further
includes a hydraulic sensor coupled to the motor or hydraulic drive
16 and configured to sense a hydraulic pressure required to turn
the mixing drum 14.
[0036] System 10 further comprises a processor or ready slump
processor (RSP) 24 including a memory 25 electrically coupled to
the hydraulic sensor 22 and the rotational sensor 20 and configured
to qualify and calculate the current slump of the concrete in the
mixing drum 14 based the rotational speed of the mixing drum and
the hydraulic pressure required to turn the mixing drum,
respectively. The rotational sensor and hydraulic sensor may be
directly connected to the RSP 24 or may be coupled to an auxiliary
processor that stores rotation and hydraulic pressure information
for synchronous delivery to the RSP 24. The RSP 24, using memory
25, may also utilize the history of the rotational speed of the
mixing drum 14 to qualify a calculation of current slump.
[0037] A communications port 26, such as one in compliance with the
RS 485 modbus serial communication standard, may be configured to
communicate the slump calculation to a status system 28 commonly
used in the concrete industry, such as, for example, TracerNET (now
a product of Trimble Navigation Limited, Sunnyvale, Calif.), which,
in turn, wirelessly communicates with a central dispatch center 44.
An example of a wireless status system is described by U.S. Pat.
No. 6,611,755, which is hereby incorporated herein in its entirety.
It will be appreciated that status system 28 may be any one of a
variety of commercially available status monitoring systems.
[0038] Alternatively, or in addition, a separate communication path
on a licensed or unlicensed wireless frequency, e.g. a 900 MHz, 433
MHz, or 418 MHz frequency, may be used for communications between
RSP 24 and the central dispatch office when concrete trucks are
within range of the central dispatch office, permitting more
extensive communication for logging, updates and the like when the
truck is near to the central office, as described below. A further
embodiment might include the ability for truck-to truck
communication/networking for purposes of delivering programming and
status information. Upon two trucks identifying each other and
forming a wireless connection, the truck that contains a later
software revision could download that revision to the other truck,
and/or the trucks could exchange their status information so that
the truck that returns first to the ready mix plant can report
status information for both to the central system. RSP 24 may also
be connected to the central dispatch office or other wireless
nodes, via a local wireless connection, or via a cellular wireless
connection. RSP 24 may over this connection directly deliver and
receive programming, ticket and state information to and from the
central dispatch center without the use of a status system.
[0039] Delivery vehicle 12 further includes a water supply 30 and
system 10 further comprises a flow valve 32 coupled to the water
supply 30 and configured to control the amount of water added to
the mixing drum 14 and a flow meter 34 coupled to the flow valve 32
and configured to sense the amount of water added to the mixing
drum 14. The water supply is typically pressurized by a pressurized
air supply generated by the delivery truck's engine. RSP 24 is
electrically coupled to the flow valve 32 and the flow meter 34 so
that the RSP 24 may control the amount of water added to the mixing
drum 14 to reach a desired slump. RSP 24 may also obtain data on
water manually added to the drum 14 by a hose connected to the
water supply, via a separate flow sensor or from status system 28.
A separate embodiment might utilize a positive displacement water
pump in place of a pressurized system. This would eliminate the
need for repeated pressurizing, depressurizing that may occur in
the present embodiment. Also, the volume of water dispensed might
be more accurately achieved. It would also facilitate direct
communication between the RSP and the pump.
[0040] As an alternative or an option, delivery vehicle 12 may
further include a chemical additive supply 36 and system 10 may
further comprise a chemical additive flow valve 38 coupled to the
chemical additive supply 36 and configured to control the amount of
chemical additive added to the mixing drum 14, and a chemical
additive flow meter 40 coupled to the chemical additive flow valve
38 and configured to sense the amount of chemical additive added to
the mixing drum 14. In one embodiment, RSP 24 is electrically
coupled to the chemical additive flow valve 38 and the chemical
additive flow meter 40 so that the RSP 24 may control the amount of
chemical additive added to the mixing drum 14 to reach a desired
slump. Alternatively, chemical additive may be manually added by
the operator and RSP 24 may monitor the addition of chemical
additive and the amount added.
[0041] Delivery vehicle 12 further includes an air supply 33 and
system 10 may further comprise an air flow valve 35 coupled to the
chemical additive supply 36 and the water supply 30 and configured
to pressurize the tanks containing the chemical additive supply and
the water supply. In one embodiment, RSP 24 is electrically coupled
to the air flow valve so that the RSP 24 may control the pressure
within the chemical additive supply and the water supply.
[0042] System 10 may also further comprise an external display,
such as display 42. Display 42 actively displays RSP 24 data, such
as slump values. The central dispatch center can comprise all of
the necessary control devices, i.e. a batch control processor 45.
Wireless communication with the central dispatch center can be made
via a gateway radio base station 43. It should be noted that the
status system display and the display 42 may be used separately
from one another or in conjunction with one another.
[0043] A set of environmentally sealed switches 46, e.g. forming a
keypad or control panel, may be provided by the RSP 24 to permit
control and operator input, and to permit various override modes,
such as a mode which allows the delivery vehicle 12 to be operated
in a less automated manner, i.e., without using all of the
automated features of system 10, by using switches 46 to control
water, chemical additive, and the like. (Water and chemical
additive can be added manually without having to make a manual
override at the keypad, in which case the amounts added are tracked
by the RSP 24.) A keypad on the status system 28 may also be used
to enter data into the RSP 24 or to acknowledge messages or alerts,
but switches 46 may be configured as a keypad to provide such
functions directly without the use of a status system.
[0044] A horn 47 is included for the purpose of alerting the
operator of such alert conditions.
[0045] Operator control of the system may also be provided by an
infrared or RF key fob remote control 50, interacting with an
infrared or RF signal detector 49 in communication with RSP 24. By
this mechanism, the operator may deliver commands conveniently and
wirelessly. Furthermore, infrared or RF signals exchanged with
detector 49 may be used by the status system 28 for wireless
communication with central dispatch center 44 or with a batch plant
controller when the truck is at the plant.
[0046] In one embodiment of the present invention, all flow sensors
and flow control devices, e.g., flow valve 32, flow meter 34,
chemical additive flow valve 38, and chemical additive flow meter
40, are contained in an easy-to-mount manifold 48 while the
external sensors, e.g., rotational sensor 20 and hydraulic pressure
sensor 22, are provided with complete mounting kits including all
cables, hardware and instructions. It should be noted that all flow
sensors and flow control devices can be mounted inline, separately
from one another. In another embodiment, illustrated in FIG. 6, the
water valve and flow meter may be placed differently, and an
additional valve for manual water may be included, to facilitate
cold weather operation. Varying lengths of interconnects 50 may be
used between the manifold 48, the external sensors 20, 22, and the
RSP 24. Thus, the present invention provides a modular system
10.
[0047] In operation, the RSP 24 manages all data inputs, e.g., drum
rotation, hydraulic pressure, flow, temperature, water and chemical
additive flow, to calculate current slump and determine when and
how much water and/or chemical additive should be added to the
concrete in mixing drum 14, or in other words, to a load. (As
noted, rotation and pressure may be monitored by an auxiliary
processor under control of RSP 24.) The RSP 24 also controls the
water flow valve 32, an optional chemical additive flow valve 38,
and an air pressure valve (not shown). (Flow and water control may
also be managed by another auxiliary processor under control of the
RSP 24.) The RSP 24 typically uses ticket information and discharge
drum rotations and motor pressure to measure the amount of concrete
in the drum, but may also optionally receive data from a load cell
51 coupled to the drum for a weight-based measurement of concrete
volume. Data from load cell 51 may be used to compute and display
the amount of concrete poured from the truck (also known as
concrete on the ground), and the remaining concrete in the drum.
Weight measurements generated by load cell 51 may be calibrated by
comparing the load cell measurement of weight added to the truck,
to the weight added to the truck as measured by the batch plant
scales.
[0048] The RSP 24 also automatically records the slump at the time
the concrete is poured, to document the delivered product quality,
and manages the load during the delivery cycle. The RSP 24 has
three operational modes: automatic, manual and override. In the
automatic mode, the RSP 24 adds water to adjust slump
automatically, and may also add chemical additive in one
embodiment. In the manual mode, the RSP 24 automatically calculates
and displays slump, but an operator is required to instruct the RSP
24 to make any additions, if necessary. In the override mode, all
control paths to the RSP 24 are disconnected, giving the operator
complete responsibility for any changes and/or additions. All
overrides are documented by time and location.
[0049] Referring to FIG. 2, a simplified flow chart 52 describing
the interaction between the central dispatch center 44, the status
system 28, and the RSP 24 in FIG. 1 is shown. More specifically,
flow chart 52 describes a process for coordinating the delivery of
a load of concrete at a specific slump. The process begins in block
54 wherein the central dispatch center 44 transmits specific job
ticket information via its status system 28 to the delivery
vehicle's 12 on-board ready slump processor 24. The job ticket
information may include, for example, the job location, amount of
material or concrete, and the customer-specific or desired
slump.
[0050] Next, in block 56, the status system 28 on-board computer
activates the RSP 24 providing job ticket information, e.g., amount
of material or concrete, and the customer-specific or desired
slump. Other ticket information and vehicle information could also
be received, such as job location as well as delivery vehicle 12
location and speed.
[0051] In block 58, the RSP 24 continuously interacts with the
status system 28 to report accurate, reliable product quality data
back to the central dispatch center 44. Product quality data may
include the exact slump level reading at the time of delivery,
levels of water and/or chemical additive added to the concrete
during the delivery process, and the amount, location and time of
concrete delivered. The process 52 ends in block 60.
[0052] Further details of the management of the RSP 24 of slump and
its collection of detailed status information is provided below
with reference to FIG. 4 et seq.
[0053] Referring to FIG. 3, a flow chart 62 describing an automatic
mode 64 for load management by the RSP 24 in FIG. 1 is shown. In
this embodiment, in an automatic mode 64, the RSP 24 automatically
incorporates specific job ticket information transmitted from the
central dispatch center 44 or from gateway 43, or entered by the
driver of the delivery vehicle, and obtains delivery vehicle 12
location and speed information from the status system 28, and
obtains product information from delivery vehicle 12 mounted
sensors, e.g., rotational sensor 20 and hydraulic pressure sensor
22. The RSP 24 then calculates current slump as indicated in block
66.
[0054] Block 67 determines if chemical additive has been manually
added. If chemical additive has been added, then the current slump
characteristics are captured and reported. Automatic water
management is then disabled. As long as chemical additive is not
manually added, automatic water management remains enabled, and in
this case, the process moves to block 68, where the current slump
is compared to the customer-specified or desired slump. If the
current slump is less than to the customer-specified slump, a
liquid component, e.g., water, is automatically added 70 to move
toward the customer-specified slump. (The amount of water added may
be less than the amount computed to create the desired slump, in
order to avoid over-watering.) It should be noted that although a
chemical additive is not automatically added, the RSP could meter
the amount of chemical additive added to the mixture. (Chemical
additive typically makes concrete easier to work, and also affects
the relationship between slump and drum motor pressure, but has a
limited life.) Once water is added, the amount of water added is
documented, as indicated in block 72. Control is then looped back
to block 66 wherein the current slump is again calculated. It
should be noted, that once a chemical additive has been added, the
relationship between slump and drum motor pressure is altered, and
RSP 24 accordingly may adjust its calculations to account for these
changes, or alternatively, discontinue automatically adding water
to adjust slump after the addition of additive, and instead simply
display slump, drum rotation, hydraulic pressure, flow, and/or
temperature.
[0055] Once the current slump is substantially equal to the
customer-specified or desired slump in block 68, the load is ready
for delivery and control is passed to block 78. In block 78, the
slump level of the product is captured and reported, as well as the
time, location and amount of product delivered. The slump level can
be captured and reported at any number of times during the process,
as well as the time, location and amount of product delivered.
Automatic mode 64 ends in block 80.
[0056] Referring now to FIG. 4, a substantially more detailed
embodiment of the present invention can be described. In this
embodiment automatic handling of water and monitoring of water and
chemical additive input is combined with tracking the process of
delivery of concrete from a mixing plant to delivery truck to a job
site and then through pouring at the job site.
[0057] FIG. 4 illustrates the top-level process for obtaining input
and output information and responding to that information as part
of process management and tracking. Information used by the system
is received through a number of sensors, as illustrated in FIG. 1,
through various input/output channels of the ready slump
processor.
[0058] In a first step 100, information received on one of those
channels is refreshed. Next in step 102, the channel data is
received. Channel data may be pressure, rotation, temperature,
tilt, and/or truck acceleration/deceleration sensor information,
water flow sensor information and valve states, or communications
to or requests for information from the vehicle status system 28,
such as relating to tickets, driver inputs and feedback, manual
controls, vehicle speed information, status system state
information, GPS information, and other potential communications.
Communications with the status system may include messaging
communications requesting statistics for display on the status
system or for delivery to the central dispatch center, or may
include new software downloads or new slump lookup table
downloads.
[0059] For messaging communications, code or slump table downloads,
in step 104 the ready slump processor completes the appropriate
processing, and then returns to step 100 to refresh the next
channel. For other types of information, processing of the ready
slump processor proceeds to step 106 where changes are implemented
and data is logged, in accordance with the current state of the
ready slump processor.
[0060] In addition to processing state changes, process management
108 by the ready slump processor involves other activities shown on
FIG. 4. Specifically, process management may include management of
the horn in step 110, management of water and chemical additive
monitoring in step 112, management of slump calculations in step
114, and management of drum rotation tracking in step 116, and
management of cold weather activity in step 118.
[0061] As noted in FIG. 4, water management and chemical additive
monitoring is only performed when water or valve sensor information
is updated, and slump calculations are only performed when pressure
and rotation information is updated, and drum management in step
116 is only performed when pressure and rotation information is
updated.
[0062] Referring now to FIG. 4A, horn management in step 110 can be
explained. The horn of the ready slump processor is used to alert
the operator of alarm conditions, and may be activated continuously
until acknowledged, or for a programmed time period. If the horn of
the ready slump processor is sounding in step 120, then it is
determined in step 122 whether the horn is sounding for a specified
time in response to a timer. Is so, then in step 124 the timer is
decremented, and in step 126 it is determined whether the timer has
reached zero. If the timer has reached zero, in step 128 the horn
is turned off, and in step 130 the event of disabling the horn is
logged. In step 122 if the horn is not responsive to a timer, then
the ready slump processor determines in step 132 whether the horn
has been acknowledged by the operator, typically through a command
received from the status system. If the horn has been acknowledged
in step 132, then processing continues to step 128 and the horn is
turned off.
[0063] Referring now to FIG. 4B, water management in step 112 can
be explained. The water management process involves continuous
collection of the flow statistics for both water and chemical
additive, and, in step 136, collection of statistics on detected
flows. In addition, error conditions reported by sensors or a
processor responsible for controlling water or chemical additive
flow are logged in step 138.
[0064] The water management routine also monitors for water leaks
by passing through steps 140, 142 and 144. In step 140 it is
determined whether the water valve is currently open, e.g., due to
the water management processor adding water in response to a prior
request for water, or a manual request for water by the operator
(e.g., manually adding water to the load or cleaning the drum or
truck after delivery). If the valve is open, then in step 142 it is
determined whether water flow is being detected by the flow sensor.
If the water valve is open and there is no detected water flow,
then an error is occurring and processing continues to step 146 at
which time the water tank is depressurized, an error event is
logged, and a "no flow" flag is set to prevent any future automatic
pressurization of the water tank. If water flow is detected in step
142, then processing continues to step 148.
[0065] Returning to step 140, if the water valve is not open, then
in step 144 is determined whether water flow is nevertheless
occurring. If so, then an error has occurred and processing again
proceeds to step 146, the system is disarmed, the water delivery
system is depressurized, a "leak" flag is set and an error event is
logged.
[0066] If water flow is not detected in step 144, then processing
continues to step 148. Processing continues past step 148 only if
the system is armed. The water management system must be armed in
accordance with various conditions discussed below, for water to be
automatically added by the ready slump processor. If the system is
not armed in step 148, then in step 166, any previously requested
water addition is terminated.
[0067] If the system is armed, then in step 152 it is determined
whether the chemical additive valve has been manually opened, e.g.,
due to the operator adding a chemical additive in order to make
working with the concrete easier. If the valve is open, then in
step 154 it is determined whether chemical additive flow is being
detected by the flow sensor. If the chemical additive valve is open
and there is no detected chemical additive flow, then an error is
occurring and processing continues to step 146 at which time the
chemical additive tank is depressurized, an error event is logged,
and a "no flow" flag is set to prevent any future automatic
pressurization of the chemical additive tank. If chemical additive
flow is detected in step 154, then processing continues to step
160. In step 160 the amount of chemical additive added is logged
and the system is disarmed. The process then moves to step block
166 whereby termination of automatic water delivery is
executed.
[0068] Returning to step 152, if the chemical additive valve is not
open, then in step 156 it is determined whether chemical additive
flow is nevertheless occurring. If so, then an error has occurred
and processing again proceeds to step 146, the system is disarmed,
the chemical additive delivery system is depressurized, a "leak"
flag is set and an error event is logged. If there is no chemical
additive flow then the process moves to block 162.
[0069] If the above tests are passed, then processing arrives at
step 162, and it is determined whether the current slump is above
target. If the slump is equal to or above target, the current slump
characteristics are logged in step 165, and the process moves to
block 166. If the current slump is below target the process moves
to step 164, it is then determined whether there is a valid slump
calculation available. If there is a valid slump calculation
available, then in the process moves to block 167. If there is not
a valid slump calculation, then no further processing takes place
and the water management process proceeds to step 165. In step 167,
it is determined whether the slump is too far below the target
value. If so, processing continues from step 167 to step 168, in
which a specified percentage, e.g. 80%, of the water needed to
reach the desired slump is computed, utilizing in the slump tables
and computations discussed herein. (The 80% parameter, and many
others used by the ready slump processor, are adjustable via a
parameter table stored by the ready slump processor.) Then, in step
169, the water tank is pressurized and an instruction is generated
requesting delivery of the computed water amount, and the event is
logged.
[0070] Referring now to FIG. 4C, slump calculation management in
step 114 can be explained. Some calculations will only proceed if
the drum speed is stable. The drum speed may be unstable if the
operator has increased the drum speed for mixing purposes, or if
changes in the vehicle speed or transmission shifting has occurred
recently. The drum speed must be stable for valid slump calculation
to be generated. In step 170, therefore, the drum speed stability
is evaluated, by analyzing stored drum rotation information
collected as described below with reference to FIG. 4D. If the drum
speed is stable, then in step 172 a slump calculation is made.
Slump calculations in step 172 are performed utilizing an
empirically generated lookup table identifying concrete slump as a
function of measured hydraulic pressure of the drum drive motor and
calculating offsets and compensation based on drum rotational
speed, type of equipment, load size and truck
tilt/acceleration/deceleration.
[0071] One example of slump calculation is described herein; in
this example, at a stable drum speed (as managed in FIG. 4D, below)
the average drum speed and pressure are used to compute slump, by
reference to a lookup table that identifies, at a reference drum
speed (e.g., three rpm), the slump value associated with each of a
wide range of hydraulic pressure measurements.
[0072] It will be noted that the relationship between pressure and
drum speed varies non-linearly; therefore, to accurately compute
slump at a different drum speed than the reference speed of the
table, a compensation must be performed. While the mixing performed
in transit from the plant is often at a relatively stable speed of
three to six rpm, in some situations much faster mixing speeds may
be used. For example, in some plants a truck, after loading, moves
to a "slump rack", where the truck is used to perform some portion
of batch processing. Frequently, at the slump rack, the truck will
perform high speed mixing, then adjust the load, then perform more
high speed mixing and finally slow down the drum to travel speed
and depart. If the slump calculations in RSP 24 are tied to a
specific drum speed, the RSP 24 will have difficulty computing
slump during this initial handling, which can require manual
management of the load by the driver, manual addition of water,
etc. and can lead to overwatering or other difficulties. To avoid
such manual management, RSP 24 needs to be able to compute slump at
widely varying drum speeds, potentially including speeds above ten
rpm, i.e., much faster than the reference speed for the lookup
table.
[0073] In order to support such higher mixing rates, an rpm
compensation may be utilized. For this computation, each truck is
assigned a calibrated rpm factor (RPMF), which represents the
decrease in average hydraulic pressure caused by an increase in
drum speed of 1 rpm. The RPMF for a given concrete truck is
typically between 4 and 10. RPMF is used to adjust the average
hydraulic pressure measured from the drum at speeds other than the
reference pressure of the table. In this way, the RSP 24 can
compute the average pressure that would be measured at the
reference drum speed, and this average pressure can then be used
with the stored table to determine slump.
[0074] Where the reference pressure of the table in the RSP 24 is 3
rpm, the relationship between hydraulic pressure and drum speed is
approximately linear over the range from 0 to 6 rpm. Thus, a drum
speed increase from 3 to 4 rpm decreases average pressure by
approximately 1*RPMF and a drum speed increase from 3 to 5 rpm
decreases average pressure by approximately 2*RPMF. A drum speed
decrease from 3 to 2 rpm increases average pressure by
approximately l*RPMF.
[0075] Because there is a nonlinear relationship between drum speed
and pressure, this linear approximation of average pressure change
is accurate only at speeds near to the reference speed of 3 rpm. At
higher drum speeds, the RPMF increases. For the purposes of slump
calculation, the increase in the RPMF is handled in a piecewise
linear fashion. Specifically, at drum speeds from 6 to 10 rpm, the
RPMF is doubled and above 10 rpm, the RPMF is quadrupled.
[0076] Thus, for example, if the current average drum speed is 12
rpm, then the increase in average pressure that would be expected
at a drum speed of 2 rpm is computed as follows:
[0077] For the 2 rpm decrease from 12 to 10 rpm, pressure increases
2*4*RPMF
[0078] For the 4 rpm decrease from 10 to 6 rpm, pressure increases
4*2*RPMF
[0079] For the 3 rpm decrease from 6 to 3 rpm, pressure increases
3*RPMF
[0080] Total=19*RPMF
[0081] If the RPMF for the particular truck is 6 and the measured
pressure at 12 rpm is 1500, then the pressure decrease to be
expected would be 19*RPMF=114, and the expected pressure at 3 rpm
would be 1500-114=1386.
[0082] As a second example, if the current average drum speed is 1
rpm, then the decrease in average pressure that would be expected
at a drum speed of 3 rpm is computed as follows:
[0083] For the 2 rpm increase from 2 to 3 rpm, pressure decreases
by 2*RPMF
[0084] If the RPMF for the particular truck is 8 and the measured
pressure at 2 rpm is 1200, then the pressure increase to be
expected would be RPMF=8, and the expected pressure at 3 rpm would
be 1200+8=1216.
[0085] The expected pressure at 3 rpm, computed in this manner, can
then be used with the pressure/slump table in RSP 24 to identify
the current slump.
[0086] As noted, the rpm factor RPMF is different from one truck to
another. This is for a variety of reasons including the buildup in
the drum of the truck, fin shape, hydraulic efficiency variation,
and others. Calibrating and re-calibrating the RPMF for each truck
in a fleet could be a burdensome process. However, the need for
such may be reduced by the use of a self calibration process, based
upon a theory of slump continuity. The theory of slump continuity
is that, over a short period of time, absent extraneous factors
such as addition of water or mixture, slump remains relatively
constant even if drum speed changes. Therefore the rpm compensation
described above may be tested whenever there is a drum speed
change, by comparing an observed change in average pressure caused
by the drum speed change, to the predicted change in average
pressure. If the predicted pressure change is erroneous, the rpm
factor RMPF may be adjusted.
[0087] Drum speed changes may occur at various times in a typical
delivery cycle, however, one common time that there is a drum speed
change is during the load process and slump rack premixing
described above. Specifically, at the slump rack the truck will
perform high speed mixing, then adjust the load, then more high
speed mixing, and finally slow down the drum to a travel speed of
3-6 rpm, and depart. Thus, this process presents an opportunity to
observe a transition from a high drum speed to a low drum speed,
and compare the computed pressure measurement change to the actual
pressure measurement change for that transition.
[0088] The self calibration proceeds as follows: when a drum speed
change from a higher to a lower speed occurs, the average pressure
at the higher speed (before the speed change) is used to compute a
predicted pressure at 3 rpm, and the average pressure at the lower
speed (after the speed change) is similarly used to compute a
predicted pressure at 3 rpm, in each case using the process
described above. If the predicted 3 rpm pressure derived from the
higher speed is larger than the predicted 3 rpm pressure derived
from the lower speed, this indicates that the RPMF overestimating
the pressure increase caused by speed reduction, and the RPMF is
reduced so that the two predicted 3 rpm pressures are equal. If the
predicted 3 rpm pressure derived from the lower speed is larger
than the predicted 3 rpm pressure derived from the higher speed,
this indicates that the RPMF is underestimating the pressure
increase caused by speed reduction, and the RPMF is increased so
that two predicted 3 rpm pressures are equal.
[0089] There are several safety limits applied to this self
calibration process, to ensure stability. First, the maximum amount
that the self calibration can adjust the rpm factor is plus or
minus 25% of the default value programmed for the truck. If greater
adjustments are required a technician must alter the default value
or permit larger adjustments. Furthermore, the maximum change to
the rpm factor RPMF that the self calibration can implement during
a single delivery cycle is 0.25.
[0090] Returning now to FIG. 4C, after computing a slump value in
step 172, in step 174 it is determined whether a mixing process is
currently underway. In a mixing process, as discussed below, the
drum must be turned a threshold number of times and for a
predetermined length of time before the concrete in the drum will
be considered fully mixed. If the ready slump processor is
currently counting time or drum turns, then processing proceeds to
step 177 and the computed slump value is marked invalid, because
the concrete is not yet considered fully mixed. If there is no
current mixing operation processing continues to step 178 and the
current slump measurement is marked valid, and then to step 180
where it is determined whether the current slump reading is the
first slump reading generated since a mixing operation was
completed. If so, then the current slump reading is logged so that
the log will reflect the first slump reading following mixing.
[0091] Following step 177 or step 180, or following step 170 if the
drum speed is not stable, in step 182 a periodic timer is
evaluated. This periodic timer is used to periodically log slump
readings, whether or not these slump ratings are valid. The period
of the timer may be for example one minute or four minutes. When
the periodic timer expires, processing continues from step 182 to
step 184, and the maximum and minimum slump values read during the
previous period are logged, and/or the status of the slump
calculations is logged. Thereafter in step 186 the periodic timer
is reset. Whether or not slump readings are logged in step 184, in
step 188 any computed slump measurement is stored within the ready
slump processor for later use by other processing steps, and the
slump management process returns.
[0092] Referring now to FIG. 4D, drum management of step 116 can be
explained. Drum management includes a step 190, in which the most
recently measured hydraulic pressure of the drum motor is compared
to the current rotation rate, and any inconsistency between the two
is logged. This step causes the ready slump processor to capture
sensor errors or motor errors. In step 192 a log entry is made in
the event of any drum rotation stoppage, so that the log will
reflect each time the drum rotation terminates, which documents
adequate or inadequate mixing of concrete.
[0093] In step 194 of the drum management process, rotation of the
drum in discharge direction is detected. If there is discharge
rotation, then in step 196, the current truck speed is evaluated.
If the truck is moving at a speed in excess of a limit (typically
the truck would not move faster than one or two mph during a pour
operation), then the discharge is likely unintended, and in step
198 the horn is sounded indicating that a discharge operation is
being performed inappropriately.
[0094] Assuming the truck is not moving during the discharge, then
a second test is performed in step 200, to determine whether
concrete mixing is currently underway, i.e., whether the ready
slump processor is currently counting time or drum turns. If so,
then in step 202, a log entry is generated indicating an unmixed
pour indicating that the concrete being poured appears to have been
incompletely mixed.
[0095] In any case where discharge rotation is detected, in step
204 the water system is pressurized (assuming a leak has not been
previously flagged) so that water may be used for cleaning of the
concrete truck.
[0096] After step 204, it is determined whether the current
discharge rotation event is the first discharge detected in the
current delivery process. If, in step 206, the current discharge is
the first discharge detected, then in step 208 the current slump
calculations and current drum speed are logged. Also, in step 210,
the water delivery system is disarmed so that water management will
be discontinued, as discussed above with reference to FIG. 4B. If
the current discharge is not the first discharge, then in step 212
the net load and unload turns computed by the ready slump processor
is updated.
[0097] In the typical initial condition of a pour, the drum has
been mixing concrete by rotating in the charging direction for a
substantial number of turns. In this condition, three-quarters of a
turn of discharge rotation are required to begin discharging
concrete. Thus, when discharge rotation begins from this initial
condition, the ready slump processor subtracts three-quarters of a
turn from the detected number of discharge turns, to compute the
amount of concrete discharged.
[0098] It will be appreciated that, after an initial discharge, the
operator may discontinue discharge temporarily, e.g., to move from
one pour location to another at the job site. In such an event,
typically the drum will be reversed, and again rotate in the charge
direction. In such a situation, the ready slump processor tracks
the amount of rotation in the charge direction after an initial
discharge. When the drum again begins rotating in the discharge
direction for a subsequent discharge, then the amount of
immediately prior rotation in the charge direction (maximum
three-quarters of a turn) is subtracted from the number of turns of
discharge rotation, to compute the amount of concrete discharged.
In this way, the ready slump processor arrives at an accurate
calculation of the amount of concrete discharged by the drum. The
net turns operation noted in step 212 will occur each time the
discharge rotation is detected, so that a total of the amount of
concrete discharge can be generated that is reflective of each
discharge rotation performed by the drum. As an alternative or in
addition to the computations in FIG. 212, the other sensors
available to the ready slump processor 24, including the optional
load cell 51 seen in FIG. 1, may be used to further enhance the
computation of the amount of concrete delivered from the truck
(concrete on the ground). Specifically, the change in weight
measured by the load cell may be used as a measure of the concrete
delivered. Furthermore, the temperature sensor may be used to
detect the volume of concrete in the drum by detecting the
temperature change indicative of immersion of the sensor in the hot
concrete and the emergence of the sensor from the hot concrete as
the drum is rotated. The fraction of a turn during which elevated
temperature is detected is another potential measure of the volume
of concrete in the drum.
[0099] After the steps noted above, drum management proceeds to
step 214, in which the drum speed stability is evaluated. In step
214, it is determined whether the pressure and speed of the drum
hydraulic motor have been measured for a full drum rotation. If so,
then in step 215 a flag is set indicating that the current rotation
speed is stable. Following this step, in step 216 it is determined
whether initial mixing turns are being counted by the ready slump
processor. If so, then in step 218 it is determined whether a turn
has been completed. If a turn has been completed then in step 220
the turn count is decremented and in step 222 it is determined
whether the current turn count has reached the number needed for
initial mixing. If initial mixing has been completed then in step
224 a flag is set to indicate that the initial turns been
completed, and in step 226 completion of mixing is logged.
[0100] If in step 214 pressure and speed have not been measured for
a full rotation of the drum, then in step 227 the current pressure
and speed measurements are compared to stored pressure and speed
measurements for the current drum rotation, to determine if
pressure and speed are stable. If the pressure and speed are
stable, then the current speed and pressure readings are stored in
the history (step 229) such that pressure and speed readings will
continue to accumulate until a full drum rotation has been
completed. If, however, the current drum pressure and speed
measurements are not stable as compared to prior measurements for
the same drum rotation, then the drum rotation speed or pressure
are not stable, and in step 230 the stored pressure and speed
measurements are erased, and the current reading is stored, so that
the current reading may be compared to future readings to attempt
to accumulate a new full drum rotation of pressure and speed
measurements that are stable and usable for a slump measurement. It
has been found that accurate slump measurement is not only
dependent upon rotation speed as well as pressure, but that stable
drum speed is needed for slump measurement accuracy. Thus, the
steps in FIG. 4D maintain accuracy of measurement.
[0101] Referring now to FIG. 5, the states of the ready slump
processor are illustrated. These states include an out_of_service
state 298, in_service state 300, at_plant state 302, ticketed state
304, loading state 306, loaded state 308, to_job state 310, on_job
state 312, begin_pour state 314, finish_pour state 316, and
leave_job state 318. The out of service state is a temporary state
of the status system that will exist when it is first initiated,
and the status system will transition from that state to the
in_service state or at_plant state based upon conditions set by the
status system. The in_service state is a similar initial state of
operation, indicating that the truck is currently in service and
available for a concrete delivery cycle. The at_plant state 302 is
a state indicating that the truck is at the plant, but has not yet
been loaded for concrete or given a delivery ticket. The ticketed
state 304 indicates that the concrete truck has been given a
delivery ticket (order), but has not yet been loaded. (A delivery
truck may also receive a job ticket when loading, loaded, or even
when en route to a job site.) A loading state 306 indicates that
the truck is currently loading with concrete. The loaded state 308
indicates that the truck has been loaded with concrete. The to_job
state 310 indicates that the truck is on route to its delivery
site. The on_job state 312 indicates the concrete truck is at the
delivery site. The begin_pour state 314 indicates that the concrete
truck has begun pouring concrete at the job site. It will be noted
that a transition may be made from the loaded state or the to_job
state directly to the begin_pour state, in the event that the
status system does not properly identify the departure of the truck
from the plant and the arrival of the truck at the job site (such
as if the job site is very close to the plant). The finish_pour
state 316 indicates that the concrete truck has finished pouring
concrete at the job site. The leave_job state 318 indicates the
concrete truck has left the job site after a pour.
[0102] It will be noted that transition may occur from the
begin_pour state directly to the leave_job state in the
circumstance that the concrete truck leaves the job site before
completely emptying its concrete load. It will also be noted that
the ready slump processor can return to the begin_pour state from
the finish_pour state or the leave_job state in the event that the
concrete truck returns to the job site or recommences pouring
concrete at the job site. Finally, it will be noted that a
transition may occur from either the finish_pour state or the
leave_job state to the at_plant state in the event that the
concrete truck returns to the plant. The concrete truck may not
empty its entire load of concrete before returning to the plant,
and this circumstance is allowed by the ready slump processor.
Furthermore, as will be discussed in more detail below, the truck
may discharge a partial portion of its load while at the plant
without transitioning to the begin pour state, which may occur if a
slump test is being performed or if a partial portion of the
concrete in the truck is being discharged in order to add
additional concrete to correct the slump of the concrete in the
drum.
[0103] FIGS. 6A-6F illustrate embodiments of a cold weather
operation water evacuation system. When the temperature falls below
freezing it is possible that water in the supply lines may freeze
and expand, thus damaging the lines. Thus it is necessary to
evacuate the water from the supply lines when the temperature falls
below freezing.
[0104] FIG. 6A illustrates an embodiment of a cold weather
operation water evacuation system in which a pneumatic purge method
is utilized for the evacuation of water from the supply lines. An
air supply 33 is often available on a mixing truck, but may only be
pressurized if the truck engine is running; this embodiment uses a
secondary air supply 320. Due to the use of two air supplies, a
safety hold back valve 322 can be used to regulate the pressure
between the air supplies. Also, regulators 324/326 can be used
between the air supplies and the rest of the system. The regulators
will maintain a certain pressure throughout the lines, i.e. 50 or
65 p.s.i. There are a multitude of valves used in the water
evacuation system. The air valve 35 controls the pressurization of
the water supply. There is a valve between the water supply 30 and
the air valve 35, which opens and closes the line allowing for
pressurization and depressurization of the water supply 30, an
example of a valve used could be a Humphrey type valve 336. A
safety pop-off valve 334 insures that the pressure in the water
supply 30 stays below a predetermined level, i.e. 60 p.s.i. A water
valve 32 allows water to flow into the water lines. Flow meter 34
tracks the amount of water that flows through the lines. The purge
valve 328 releases air into the lines enabling the evacuation of
water from the lines, pushing the water back into the water supply
30 without depressurization of the tank 30. The drum valve 330
allows water to flow into the drum, and can be controlled by the
RSP 24 in order to modify the slump characteristics. The hose valve
332 allows water to flow into a hose.
[0105] The embodiment of FIG. 6B is similar to that of 6A with the
exception of a chemical additive supply 36. The chemical additive
supply 36 further includes a Humphrey valve 337, a safety pop-off
valve 335, and a chemical additive valve 38. The flow meter 34/40
can be used to track the flow of both chemical additive and water
through the lines. It should be noted that in the event that
chemical additive is used the lines would first be flushed with
water before purging the lines with air.
[0106] FIG. 6C illustrates an embodiment in which a pump 338 is
used to deliver fluid throughout the system. In this embodiment
water is evacuated from the delivery lines back into the drum 14.
The purge valve 328 opens causing the pump 338 to push air through
the water delivery line into the drum 14. The drum valve 330 closes
before the air valve 35 opens allowing the pump 338 to build
pressure in the delivery line. The drum valve 330 then opens; the
pump 338 pushes air through the line forcing the remaining water
into the drum 14.
[0107] FIG. 6D is similar to that of 6C with the exception of a
chemical additive supply 36. The chemical additive supply 36
further includes a chemical additive valve 38. In the event that
chemical additive is used, the delivery lines will be flushed with
water prior to evacuation of the lines with air. The purge valve
328 opens and the water valve 32 closes causing the pump 338 to
push air through the water delivery line into the drum 14. The drum
valve 330 closes before the air valve 35 opens allowing the pump
338 to build pressure in the delivery line. The drum valve 330 then
opens; the pump 338 pushes air through the line forcing the
remaining water into the drum 14. This process can occur after
every water or additive delivery or can be performed manually via a
hand switch.
[0108] FIG. 6E is an illustration of a water evacuation system in
which the evacuation can occur while the water supply 30 is
depressurized. First, water is evacuated from the horizontal
portion of the delivery line back into the drum 14. When the water
tank 30 is depressurized, the Humphrey valve 336 exhausts stored
air pressure into the water delivery line via check valve 342. This
air pressure forces remaining water into the mixing drum 14. Check
valves 342 are used to insure the flow direction of the air
pressure that evacuates the line. After air pressure is depleted
the water valve 32 opens for a period of time to allow remaining
water to drain back into the water tank 30. Water can then be
evacuated from the rest of the delivery lines. The manual drum
valve 330 is closed, and then the water tank 30 is depressurized. A
manual valve 332 is used to shut off hose water and to port air
pressure from the water tank pneumatic supply into the hose line.
This insures the check valve 342 remains closed and that the hose
line will not refill with water when the water tank 30 is
pressurized.
[0109] FIG. 6F is similar to that of 6E with the exception of a
chemical additive supply 36. The chemical additive supply 36
further includes a chemical additive valve 38, as well as a
separate flow meter for the chemical additive. In the event that
chemical additive is used, the delivery lines will be flushed with
water prior to evacuation of the lines with air. It should be noted
that in this embodiment there is a separate flow meter for the
water and the chemical additive.
[0110] FIG. 7 illustrates the location of the mixing drum access
door 518 on the mixing drum 14. The mixing drum access door 518 is
a convenient location for a temperature sensor such as a dual
temperature sensor 17 elaborated below. In the disclosed
embodiment, the sensor is attached to the exterior of the access
door. In other embodiments, the sensor could be attached elsewhere
on the concrete drum other than the exterior portion of the access
door, and may be attached to other concrete mixing equipment such
as a stationary drum or a portable mixer. Furthermore, in
alternative embodiments, a noncontact temperature sensor, such as
an infrared sensor, may be used to measure the temperature of the
load without requiring contact therewith.
[0111] Referring now to FIG. 8, the sensor mounted to the mixing
drum access door 518 may use a dual temperature sensor mount 530.
The load temperature sensor 526 could be a thermocouple which
protrudes through the center of the mount, through the mixing drum
access door skin and into the load. It should be noted that the
load sensor is insulated from the mount and the drum skin. The load
sensor is hardened using a plasma spray process and streamlined to
permit a smooth flow of the load over the sensor. The plasma spray
process used for hardening the sensor uses inert gas--usually
nitrogen or argon--excited by a pulsed DC arc to ionize the gas and
produce plasma. Other gasses--mainly hydrogen and helium--are often
introduced in small quantity in order to increase the ionization.
The plasma gasses are introduced at high volume and high velocity,
and are ionized to produce a plume that ranges in temperature from
about 12,000.degree. to 30,000.degree. F. Powder feedstock is then
injected into this hot gas stream (called a plume), heated very
quickly, and deposited onto the work piece. Thermal spray coatings,
more specifically plasma spray, are often used to protect against
abrasion, erosion, adhesive wear, fretting, galling, and
cavitation. Abrasion and erosion are regularly addressed using
tungsten carbide coatings along with a series of superalloys. The
plasma spray process is available through CTS 5901 Creek Road
Cincinnati, Ohio 45242. The skin temperature sensor 528 also could
be a thermocouple, which protrudes through the corner of the mount,
and makes contact with the mixing drum skin. Circuit board 524 is
affixed to the dual temperature sensor mount 530 using four screws,
and contains the thermocouple control and the radio transmitter
control. A radio antenna 522 is attached to the circuit board. The
dual temperature sensor cover 520 is affixed to the dual
temperature sensor mount 530 using four screws. The dual
temperature sensor could be battery powered.
[0112] Using a temperature sensor, temperature readings taken from
the mixing drum, can be utilized as a factor when calculating the
slump profile. It should also be noted that a separate device could
be used in measuring the ambient air temperature. Furthermore, the
load temperature may be used to identify, from among a group of
loads, which are hottest and thus determine the order in which the
loads should be poured. Furthermore, the time left until a load
will set, and the effect or need for additives, can be derived from
load temperature. Finally, the temperature profile measured by the
sensor as the drum is rotating may be used to identify the load
size as noted above.
[0113] FIG. 9 illustrates the relationship between the hydraulic
mix pressure applied to a drum of ready mix concrete and the slump
of the concrete. The relationship is dependent on the revolutions
per minute of drum rotation. As the RPMs increase the relationship
becomes more linear in nature, as the RPMs decrease the
relationship becomes more logarithmic. It should be noted that
there are other factors that can affect the slump profile. Some of
these factors are truck tilt, load size, load weight, truck
hydraulic equipment and truck acceleration/deceleration.
Relationships utilizing these factors could be taken into account
when developing a slump profile.
[0114] FIG. 10 illustrates the relationship between concrete energy
release rate and time as it pertains to mix composition. The
information is adapted from an article published in the April 2006
edition of Concrete International, authored by Hugh Wang, C. Qi,
Hamid Farzam, and Jim Turici. The integral of the area under the
release rate curves, is the total released heat during the
hydration process. The total amount of heat released is related to
the cement reactivity which, in turn, reflects the strength
development of the concrete. Therefore utilizing the dual
temperature sensor 17 to obtain a temperature reading with respect
to time within the mixing drum 14 could be used to determine the
strength of the cured concrete. It should be noted that the
wireless nature of the dual temperature sensor permits the ready
use of the sensor on a rotating drum without the difficulties
associated with establishing wired connections from the sensor to a
control console. Furthermore, as noted above, a wireless sensor as
described herein may be utilized in conjunction with other types of
mixers, not limited to concrete trucks, such as stationary or
portable or semi-portable rotating mixers.
[0115] As noted above, various statistics and parameters are used
by the ready slump processor in operation. These statistics and
parameters are available for upload from the processor to the
central office, and can be downloaded to the processor, as part of
a messaging operation. Some values are overwritten repeatedly
during processing, but others are retained until the completion of
a delivery cycle, as is elaborated above. The above-referenced US
patent application incorporates a specific listing of statistics
and parameters for one specific embodiment of the invention, and
other selections of parameters and statistics may be gathered as
well.
[0116] While the present invention has been illustrated by a
description of embodiments and while these embodiments have been
described in some detail, it is not the intention of the Applicants
to restrict or in any way limit the scope of the appended claims to
such detail. Additional advantages and modifications other than
those specifically mentioned herein will readily appear to those
skilled in the art.
[0117] For example, the status monitoring and tracking system may
aid the operator in managing drum rotation speed, e.g., by
suggesting drum transmission shifts during highway driving, and
managing high speed and reduced speed rotation for mixing.
Furthermore, fast mixing may be requested by the ready slump
processor when the concrete is over-wet, i.e., has an excessive
slump, since fast mixing will speed drying. It will be further
appreciated that automatic control of drum speed or of the drum
transmission could facilitate such operations.
[0118] The computation of mixing speed and/or the automatic
addition of water, may also take into account the distance to the
job site; the concrete may be brought to a higher slump when
further from the job site so that the slump will be retained during
transit.
[0119] Further sensors may be incorporated, e.g., an accelerometer
sensor or vibration sensor such as shown in FIG. 6 may be utilized
to detect drum loading as well as detect the on/off state of the
truck engine. Environmental sensors (e.g., humidity, barometric
pressure) may be used to refine slump computations and/or water
management. More water may be required in dry weather and less
water in wet or humid weather.
[0120] A warning may be provided prior to the automatic addition of
water, so that the operator may prevent automatic addition of water
before it starts, if so desired.
[0121] Finally, the drum management process might be made
synchronous to drum rotation, i.e., to capture pressure at each
amount of angular motion of the drum. Angular motion of the drum
might be signaled by the magnetic sensor detecting a magnet on the
drum passing the sensor, or may be signaled from a given number of
"ticks" of the speed sensor built into the motor, or may be
signaled by an auxiliary processor coupled to a wireless
accelerometer based drum rotation sensor. To facilitate such
operation it may be fruitful to position the magnetic sensors at
angularly equal spacing so that the signal generated by a magnet
passing a sensor is reflective of a given amount of angular
rotation of the drum.
[0122] While the present invention has been illustrated by a
description of various embodiments and while these embodiments have
been described in considerable detail, it is not the intention of
the applicants to restrict or in any way limit the scope of the
appended claims to such detail. Additional advantages and
modifications will readily appear to those skilled in the art. The
invention in its broader aspects is therefore not limited to the
specific details, representative apparatus and method, and
illustrative examples shown and described. For example, all of the
above concepts can apply to both front and rear discharge
trucks.
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