Abstract:
A digital control system for monitoring and controlling a concrete pumping system. A microcontroller provides control signals and receives feedback from associated comparator switch subsystems. Feedback from the comparator switch subsystems is used by a microcontroller to determine whether short circuit or open circuit malfunctions are occurring on solenoids valves attached to the output of the comparator switch subsystems. Said control system exhibits an electronic control means to control the admittance or interruption of current through said solenoids. Individual solenoid status is sent to a graphical display where an operator views said display to diagnose failure modes. The microcontroller further monitors the establishment of temporal initial conditions and limits operational pump activity until said temporal conditions are met.

Description:
FIELD OF THE INVENTION 
       [0001]    The invention generally relates to an automated monitoring control system for a hydraulic driven pump, and more particularly to a hydraulic driven concrete pump used to pump concrete at a job site. The system monitors current flow to various solenoids and valves in the hydraulic drive to provide immediate diagnostic information, and sends control signals to the solenoids and valves based upon the monitored condition. 
       BACKGROUND OF THE INVENTION 
       [0002]    In the concrete delivery industry, delivery of concrete to the job site often requires the delivery vehicle to be at a much different lateral distance and/or elevation than a particular region of the site that is to receive concrete. To overcome this obstacle concrete placement pumps are often employed to move the concrete over the distance required. 
         [0003]    Within these concrete placement pumps, the concrete is pumped through a long tube affixed to the outlet of concrete placement pump moved to the delivery area for the concrete. To transport concrete through the steel tubing or hoses over the distance needed, large hydraulically driven piston pumps are used. 
         [0004]    One of the most common modes of failure for the concrete trucks is an obstruction in the concrete pumping line. When an obstruction, occurs the system ceases to operate and no longer expels concrete to the region of interest. Unfortunately this effect behaves identically to other failure modes. If one of the controlling solenoids within the hydraulic drive develops a fault and no longer operates as desired, the drive will no longer be able to push the concrete pump. Once a failure mode occurs the crew must wait for a technician to arrive on the jobsite. Said technician can then begin troubleshooting this event to discover whether an obstruction in the line exists, or if the pumping system has a failed solenoid. Frequently, the issue is simply an obstruction; however time and resources are utilized to inquire the possibility of failed solenoid. Additionally, during time needed for the technician to arrive on site many times the concrete will harden causing serious damage to the concrete placement pump. 
         [0005]    Oftentimes, the time required for an individual to reach the job site to troubleshoot and perform maintenance on the pumping system is too long. The concrete in the pump and the line will harden if left to sit too long. Once the concrete sets in this manner, the hardened concrete becomes incredibly difficult to remove. This costs a significant amount of time and recourses as well as the loss of time spent on the job site. 
         [0006]    Another issue plaguing the concrete boom delivery industry is engine load during start up of the engine and on/off concrete pumping cycles during daily operation while concrete is in the pumping line. At start up, hydraulic loads on the engine can be very high. These loads can overtax the engine starter and engine battery capacity. In addition, during on/off concrete pumping cycles while equipment of the concrete hoses are being moved the engine RPM is reduced to idle speeds to increase engine longevity and reduce fuel consumption. When the concrete pump is actuated from these off cycles the loads are influenced by latent pressure in the drive system and the inertia involved in moving concrete from a resting position. Often the latent loads are sufficient enough to cause the engine to lug or stall. Over time these loads on the engine can cause damage to the engine itself, requiring repair or replacement. 
         [0007]    The operational theory of said concrete pumps is fairly simple, and most failures modes are caused by loose wiring connections, broken wires, or faulty solenoids. This allows troubleshooting of wiring circuits or the replacement of solenoids to be carried out by pump operators already on the job site. The difficult part of maintaining the pumps is troubleshooting and fault analysis, which often requires trained technicians. What is needed in the industry is a way to automate the troubleshooting process to allow personnel on-site to quickly establish the cause of a failed pump and carry out appropriate maintenance procedures before the concrete in the pump system hardens. 
       SUMMARY OF THE INVENTION 
       [0008]    What is provided is a digital control system for monitoring and controlling a hydraulic driven concrete pump used to pump concrete at a job site. Currently, the ability to troubleshoot failed sub systems during operations of a pump requires a trained technician to make a service call. This may take too long as the concrete could set in the pump or tube and become hard. The current invention displays on an illuminated screen electric components, and wiring subsystems that are functioning improperly, which allows immediate diagnosis on the job site. 
         [0009]    If all the subsystems are exhibiting no failure codes as provided by the display, an operator can assume there is a clog in the line. If the system does sense a malfunctioning wiring connection or solenoid, the solenoid and the solenoid&#39;s failure state will be apparent on the user&#39;s display. With this information, a pump operator can replace or reconnect the failed solenoid without the assistance of an on-site technician. 
         [0010]    If all the subsystems are exhibiting no failure codes as provided by the display, an operator can assume there is a clog in the line. If the system does sense a malfunctioning wiring connection or solenoid, the solenoid and the solenoid&#39;s failure state will be apparent on the user&#39;s display. With this information, a pump operator can replace or reconnect the failed solenoid without the assistance of an on-site technician. 
         [0011]    The system also reduces load on the engine driving the pump during startup. This minimizes the load on the engine starter and battery and therefore increases its operational lifetime. The system also delays the activation of the concrete placement pump when the engine is at idle allowing the engine to reach full RPM and maximum horsepower before the full load is applied the engine. This prevents engine lugging and sometimes engine stalling, thus increasing the engines operational life. 
         [0012]    The objectives, features, and attendant advantages of the invention will become apparent as the invention becomes better understood by reference to the following detailed descriptions and accompanying drawings. The detailed description and drawings illustrate some, but not the only, embodiments of the invention. 
     
    
     
       BRIEF DESCRIPTION ON THE DRAWINGS 
         [0013]      FIG. 1  shows an embodiment of the digital control system interfaced with a basic concrete pumping apparatus in schematic format. 
           [0014]      FIG. 2  shows an embodiment of the microcontroller subsystem of the invented digital control system in block diagram format. 
           [0015]      FIG. 3  shows an embodiment of a comparator switch circuit of the invented digital control system in block diagram format. 
           [0016]      FIG. 4  shows an embodiment of a motorized flow control circuit of the invented digital control system in block diagram format. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0017]    While the invention is susceptible of various modifications and alternative constructions, certain illustrated embodiments thereof have been shown in the drawings and will be described below in detail. It should be understood, however, that there is no intention to limit the invention to the specific form disclosed, but, on the contrary, the invention is to cover all modifications, alternative constructions, and equivalents falling within the spirit and scope of the invention as defined in the claims. 
         [0018]    To deliver concrete to a job site impassable by delivery trucks, concrete placement pumps are utilized. These pumps move concrete through a tube to the region to receive the concrete. To facilitate this pumping, hydraulically driven piston pumps flow oil through hydraulic valves which are controlled by electric solenoids. These hydraulically driven piston pumps exhibit many different failure modes in their lifetime. Of these failure modes, the most common is either a clog in the line or a failed solenoid. Both of these failure modes exhibit the same symptoms. A technician is required on-site to troubleshoot the failure mode to determine whether it is either a clog in the line or a failed solenoid. This creates a waste of time and resources to diagnose the issue. Another issue these concrete pumps face is high engine loads at start up. These engines loads are caused by latent pressure within the system that cause a load upon the piston pumps. Repetitious high-load startups can reduce the lifetime of the engine&#39;s starter motor and reduce battery life. 
         [0019]    The current invention addresses these issues by monitoring and controlling the various solenoids and motors associated with a hydraulic drive system. The monitored status of the various solenoids are then displayed to a user in graphical format on a display screen. If a failure symptom occurs, the operator of the pump can then review the data display to determine the source of the failure. The display data will then inform the operator if the failure is the cause of a broken subsystem or a clog in the line. 
         [0020]    If all the subsystems are showing no error messages, meaning none of the solenoids are exhibiting shorts or opens, then the result follows that there is a clog in the line. If the system does sense a malfunctioning solenoid, the solenoid and the solenoid&#39;s failure state will be apparent on the user&#39;s display. 
         [0021]    The system also establishes initial conditions that must be met before activation of the pump. To reduce the engine starting load, the control system closes a motorized flow control valve and opens an actuator dump valve. This minimizes the load on the engine and therefore increases its operational lifetime and prevents high speed pumping of the concrete before the lines are filled with concrete. Most plugs of the concrete lines occur during this initial filling period. 
         [0022]    In the following description and in the figures, like elements are identified with like reference numerals. The use of “or” indicates a non-exclusive alternative without limitation unless otherwise noted. The use of “including” means “including, but not limited to,” unless otherwise noted. 
         [0023]      FIG. 1  illustrates the digital control system of the current invention interfaced with a basic concrete pumping apparatus. Engine  15  provides power to hydraulic drive system  19  through drive line  53 . Engine  15  also sends a signal to control system  49  when engine  15  is initialized, said signal is sent over engine to control system signal line  51 . Digital control system  49  monitors and controls solenoids located in accumulator  27 , shuttle  37 , and piston assemblies  23  and  25 . 
         [0024]    Digital control system  49  further controls the motorized flow control valve  63 . Hydraulic drive system  19  is configured to supply pressurized hydraulic fluid to accumulator  27  and piston assemblies  23  and  25  through hydraulic line assembly  21 . In turn accumulator  27  supplies hydraulic pressure to shuttle  37  through accumulator to shuttle hydraulic line  29 . 
         [0025]    The magnitude of the hydraulic pressure actuating shuttle  37  and piston assemblies  23  and  25  is modulated by a motorized flow control valve  63 . Said motorized flow control valve  63  controls the volume of hydraulic fluid incoming to hydraulic drive system  19 . The more hydraulic fluid admitted into hydraulic drive system  19  by said motorized flow control valve  63 , the higher the concrete pumping volume is. If less hydraulic fluid is admitted through said motorized flow control valve  63 , then the concrete output of the pump decreases. Digital flow control system  49  actuates the position of the motorized flow control valve  63  through signal bus  47 . 
         [0026]    Accumulator  27  is configured to vent pressure to the hydraulic tank when the pump system is initialized. This is accomplished by a solenoid actuated accumulator dump valve  59 . Digital control system  49  is configured to open said accumulator dump valve  59  by sending a signal on control system to accumulator signal line  17  upon engine  15  startup. 
         [0027]    Piston assemblies  23  and  25  are hydraulically actuated with solenoid valves  55  and  57  controlled by control system  49 . An activation or deactivation signal is sent to the solenoids  55  and  57  through control system to piston assembly solenoid lines  43  and  45 . By actuating the hydraulic pressure to piston assemblies  23  and  25 , said piston assemblies are configured to operate by moving in an opposing linear motion within piston tubes  31  and  41 . For example, when piston assembly  23  is in a draw stroke and moving towards the closed end of piston tube  31 , piston assembly  25  will be in a compression stroke pushing toward the open end of piston tube  41 . Consequently when piston assembly  25  is in a draw stroke, piston assemble  23  will be in a compression stroke. 
         [0028]    In a preferred embodiment, piston tube intake  33  is located in a hopper filled with concrete. When piston assemblies  23  or  25  are in a draw stroke, concrete is drawn into the piston tube associated with said piston assembly. Shuttle  37  is hydraulically actuated by a solenoid valve  37  controlled by control system  49  through control system to shuttle solenoid signal line  39 . Control system  39  is configured to send a signal solenoid  61  to actuate shuttle  37  to align the pump output  35  to the cylinder tube that under a compression stroke. The aligning of shuttle  37  in this way exposes the opposite cylinder tube, which is under a draw stroke, to be exposed to a hopper full of concrete, in turn filling said tube under a draw stroke with concrete. Piston assemblies  23  and  25  along with shuttle  37  continuously cycle in this manner during operation, resulting in a continuous flow of concrete from pump output  35 . 
         [0029]    Status of the solenoid valves interfaced with said control system is displayed on display  57 . Display  57  is configured so an operator will view said display to review the operational status of said concrete pump. If a solenoid valve is experiencing a malfunction, display  57  is configured to shows the actuation state of the solenoid, proximity sensor, or the particular malfunctioning solenoid/wiring system and said malfunctioning wiring/solenoid&#39;s mode of failure. These failure modes include short circuit, and open circuit malfunctions. 
         [0030]      FIG. 2  illustrates the microcontroller circuit sub-system of the current invention. Microcontroller  13  sends activation and de-activation signal data to the comparator switch circuit seen in  FIG. 3 . It is also configured to receive current and voltage feedback data from the comparator circuit seen on  FIG. 3  and respond to said data. To send signal activation or de-activation data, microprocessor  13  sends the signal over microcontroller to load serial shift register signal bus  12  to serial shift register  14 . Signal bus  12  also clock pulse signals to serial shift register  14  to load the various registers within the serial shift register, and send the data contained in those registers across serial shift register to Darlington array signal bus  16  to Darlington array  18 . The serial activation or deactivation signal data is sent across signal bus  12  to serial shift register  14  on each corresponding clock pulse sent from microcontroller  13 . 
         [0031]    Each individual register contained in serial shift register  14  contains the signal data for each corresponding comparator switch. Serial bus  12  sends another bus clock pulse which commands the sending of parallel data from the serial shift register  14  to Darlington array  18  over serial shift register to Darlington array signal bus  16 . Darlington array  18  has a plurality of outputs. Said Darlington array outputs are represented by Darlington array signal output bus  20  and Darlington array signal output to comparator switch line  22 . 
         [0032]    Output bus  20  represents a number of similar outputs that lead to various comparator switch circuits of the form as seen in  FIG. 3 . In this manner multiple comparator switch circuits as seen in  FIG. 1  can be connected to microcontroller subsystem  FIG. 2  to allow the monitoring and controlling of any number of solenoids. 
         [0033]      FIG. 3  illustrates the comparator switch sub system of the current invention. The Darlington array signal output to comparator switch line  22  transmits the activation or deactivation signal to the comparator switch. Based upon this signal, the comparator switch generates voltage to comparator switch output  66  in turn providing the current needed to operate either an attached solenoid or a motor to the output line  66 . The output current to solenoid valves is monitored by the microcontroller system and will automatically open the connection to the solenoid valve if a short is detected. If a short is detected, the microcontroller will further pass a signal to an attached display. Said display in turn presents a graphical interface for an operator, informing said operator that a particular solenoid valve is malfunctioning as well as displaying the mode of failure. 
         [0034]    This comparator switch circuit of  FIG. 3  provides an output for the load to the solenoid valve on the machine  60  and another much smaller output that is proportional to the load current. If the sense output goes over a predetermined level, the comparator switch shuts down. If this occurs, the microcontroller  13  will detect that it is commanding an output but the voltage feedback is not conforming to the output. This condition is interpreted as a short in the load by the microcontroller  13 . In turn the microcontroller  13  will send a deactivate signal to a comparator switch. The voltage feedback is determined by voltage feedback resistors  72  and  74 . The ratio to these resistors determines the level of voltage feedback to the microcontroller  13 . The microcontroller  13  responds to this given feedback by comparing it to predetermined levels programmed in said microcontroller  13 . 
         [0035]    Microcontroller  13  detects if an open circuit or an incomplete electrical flow path exists from the microcontroller  13  to a solenoid valve and then to ground. When this open circuit is detected an error message will be displayed on display  57  indicating that there is an open circuit for that specific solenoid wiring loop. The system achieves this feature by further using the comparator switch sub assembly  FIG. 3 . Comparator switch  78  in the preferred embodiment is an IR3315 integrated circuit. The comparator circuit provides an output for the, load being a solenoid valve or motor, and another much smaller output that is proportional to the load current. The output proportional to a load current is provided on current feedback signal to multiplexer line  30 . This proportional voltage can be adjusted by selecting various values for resistor  76 , in this case to 1.5 K ohm. Since this sense output is proportional to the load, it is monitored by the microcontroller as an analog value. If the microcontroller commands an output and the monitored current feedback is to low an open circuit error is reported. This open circuit malfunction will be displayed on the graphical display to the operator designating the particular solenoid loop that is failing. 
         [0036]    The open circuit feedback signal is sent on current feedback signal to multiplexer line  30  to multiplexer  36 . Multiple comparators switch circuits operating multiple solenoid valves and motors also have their current feedback signal sent to multiplexer  26  through multiplexer current feedback bus  32 . Microcontroller  13  polls the parallel data being sent to multiplexer  26  through microcontroller to multiplexer signal bus  28 . This parallel data is then sent serially through multiplexer to microcontroller signal bus line  11 , depending on the corresponding signal pulled by microcontroller  13 . Data indicating a short is sent to microcontroller via voltage feedback to parallel load serial shift register line  46 . 
         [0037]    Multiple comparator switch circuits as seen in  FIG. 3  can also have their voltage feedback line connected to parallel load serial shift register voltage feedback bus  48 , thus multiple solenoid valves are monitored and controlled in this configuration. Microcontroller  13  sends clock pulse signal data to parallel load serial shift register  44  via microcontroller to parallel load signal shift register bus  40 . On said clock pulse the data is loaded from the input to the parallel load signal shift register line  46  and bus  48  to the registers within the serial shift register. Parallel data from line  46  and bus  48  is sent over parallel load serial shift register  44  to microcontroller  13  over parallel load serial shift register to microcontroller signal line  42 . This data is constantly polled and reviewed by microcontroller  13 . When a short circuit signal malfunction has been read from the parallel load serial shift register  44  microcontroller  13  will then send this information to display  57  via microcontroller to display line  10  to allow the operator of the device to diagnose the malfunction of that particular solenoid valve as a short. 
         [0038]      FIG. 4  is an illustration of the motorized flow control circuit of the current invention. The microcontroller  13  also controls the operation of the motorized flow control valve  63 . Said motorized flow control valve controls the amount of hydraulic fluid flowing into the hydraulic drive system  19 , thus controlling the amount of power delivered to the connected concrete pump. Microcontroller  13  energizes the motorized flow control valve  63  to close for eight seconds whenever the microcontroller  13  is initially energized. Microcontroller  13  further energizes the motorized flow control valve  63  to close whenever the starter solenoid of the engine is activated. Motorized flow control valve  63  further has an end of stroke switch which internally disengages power to said motorized flow control valve  53  when it reaches its full closed position. 
         [0039]    Closing the motorized flow control valve upon activation reduces the horse power drag on the engine during start up conditions. Microcontroller  13  achieves this feature by an internally timer that increments by every one millisecond. Upon initial power up, the microcontroller energizes the microcontroller to motorized flow signal line  38  and a comparator switch circuit as seen in  FIG. 3  whose output is connected to node  60  which allows current to pass through the flow motor. Activation signal on line  38  activates the transistor  52  which allows current flow from the comparator switch to node  60  through the motor into ground, activating the flow motor. The motor in turn closes said motorized flow control valve. When the timer in the microprocessor reaches 8,000 milliseconds (eight seconds) the microcontroller de-energizes line  38  and the comparator switch whose output is connected to node  60 , which stops motorized flow control valve  63 . 
         [0040]    Microcontroller  13  de-energizes the normally opened accumulator dump valve solenoid  59  for three seconds whenever the starter solenoid of the engine is energized. This release of latent pressure within the accumulator reduces horse power drag on the engine during start up. Said microcontroller  13  accomplishes this feature by an internal timer that increments by every millisecond. Said microcontroller  13  monitors a start wire voltage on line  51 . When it detects voltage on said line, it sets the timer to zero the code and de-energize the comparator switch circuit as seen in  FIG. 3  associated with the accumulated dump valve solenoid until the timer reaches 3,000 milliseconds (three seconds). 
         [0041]    In a preferred embodiment, a wireless communication device is incorporated with said digital control system, wherein said wireless communication device sends fault data to a remote location. At said remote location, said fault data is reviewed by technicians who can respond to malfunctions and advise operators to repair said malfunctions remotely. 
         [0042]    The exemplary embodiments shown in the figures and described above illustrate but do not limit the invention. It should be understood that there is no intention to limit the invention to the specific form disclosed; rather, the invention is to cover all modifications, alternative constructions, and equivalents falling within the spirit and scope of the invention as defined in the claims. For example, while the exemplary embodiments illustrate the control and monitoring of concrete pumps, the invention is not limited to use with the concrete industry and may be used with other pumping apparatuses. While the invention is not limited to use with concrete pumps, it is expected that various embodiments of the invention will be particularly useful in such devices. Hence, the foregoing description should not be construed to limit the scope of the invention, which is defined in the following claims. 
         [0043]    While there is shown and described the present preferred embodiment of the invention, it is to be distinctly understood that this invention is not limited thereto but may be variously embodied to practice within the scope of the following claims. From the foregoing description, it will be apparent that various changes may be made without departing from the spirit and scope of the invention as defined by the following claims.