Patent Application
20110153142
The invention relates to the control of hydraulic power take-off systems for motor vehicles and more particularly to application of such control to hydraulic power take systems for a vehicle mounted cement mixer drum.
Contemporary trucks are often equipped for power takeoff operation (PTO). PTO is used with auxiliary systems such as hoists, lifts, and pumps that are directly or indirectly powered by the vehicle's engine. Indirectly powered systems, such as hydraulic systems, are among the most popular. Power for an auxiliary hydraulic system is converted from engine output by an engine driven hydraulic pump. The hydraulic pump draws working fluid from a tank and supplies fluid to a hydraulic valve manifold which can divert the working fluid to a cylinder or impeller used to move a target load.
Original vehicle manufacturers have long supplied general purpose hydraulic pumps with their vehicles which are suitable for supporting hydraulic power take off operation. In the past the provision of controls and hydraulic lines was generally left to after market specialists. Retrofitted controls have sometimes left something to desired in terms of integration of the new wiring and hydraulic lines required.
Vehicle system integrated hydraulic power take-off systems utilizing modular components and requiring minimum modification of the vehicle have been recently developed as described in U.S. Patent Publication 2005/0206113, which is assigned to the assignee of the present invention and incorporated herein by reference. The Patent Publication teaches a system which includes a hydraulic fluid tank, a hydraulic valve manifold, an engine driven pump, and a switch and instrument panel. The system is suitable for a variety of applications. The control aspects of these systems, which are integrated with a vehicle controller area network (CAN), are of particular interest. These systems include a hydraulic valve controller and an auxiliary gauge and switch controller for connection to the vehicle controller area network and which provide integration of control over hydraulic system operation with vehicle operation. Control protocols are adapted from standard SAE J-1939 bus signals. Other vehicle controllers are monitored for standard signals for implementing interlocks as required and signals relating to engine controller control over the engine are readily invoked.
Operators of cement mixers need to know the mixer barrel rotation count and the rotational velocity of the mixer barrel to ensure mixing the cement properly. For a cement mixer mounted on a vehicle the rotational velocity of the mixer barrel must be monitored and kept at a constant rate while a charge is transported. Current mixer systems monitor mixer barrel speed using a speed sensor system that is mounted to the barrel. The sensor system requires an additional sensor and a tone ring to implement which raises reliability issues and which add to cost. Rotational velocity information is displayed to the driver/operator who must make the adjustments required to keep the operation within defined limits.
According to the invention there is provided a vehicle system integrating control of over a power take-off driven, vehicle mounted cement mixer with a vehicle controller network to monitor vehicle operating variables which are used in turn to determine cement mixer barrel rotational speed and barrel rotation count. There is no need to use direct sensing of barrel operation. The system also provides for maintaining barrel rotation at a constant speed during transportation.
Additional effects, features and advantages will be apparent in the written description that follows.
The novel features believed characteristic of the invention are set forth in the appended claims. The invention itself however, as well as a preferred mode of use, further objects and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying drawings, wherein:
Referring now to the figures and particularly to
Pump 50 is powered by vehicle engine 52 through a mechanical linkage 54 to the engine crankshaft (not shown). PTO operation may be enhanced by utilizing an engine control unit (ECU) 58 which monitors engine operating variables using engine sensors 56. While engine sensors 56 are illustrated as being direct intermediaries between ECU 58 and engine 52, related instruments, such as a tachometer, may in fact be connected to the transmission 65, with the resulting signal provided directly to the ECU or indirectly to the ECU through a transmission controller 64 over controller area network (CAN) bus 60. Integration of the components is preferably provided by a program resident on and executed by an electrical system controller (ESC) 62 and communicating with other controllers over CAN bus 60. CAN bus 60 preferably conforms to the SAE J1939 standard. Communication between the valve system controller 40 and an auxiliary gauge and switch package (AGSP) 68 to an operator interface (i.e. panel 18) is provided by CAN bus 60. CAN bus 60 typically provides a physical backbone comprising a twisted pair (either shielded or unshielded) cable operating as a data link or serial data bus. ESC 62 manages the assorted vocational controllers (e.g. valve system controller 40 and ECU 58) connected to bus 60 as nodes. Based on data received from the valve pack manifold 34 and passed to the ESC 62, coupled with knowledge about the capacity of pump 50 (pump 50 typically is an engine driven pump providing 12 gallons per minute flow at 3000 psi at a given engine speed), the ESC 62 can estimate the rotational velocity and rotation count of barrel 110.
The SAE J1939 protocol defines a number of messages which may be readily adapted to serve the requirements of a hydraulic PTO system. The auxiliary gauge and switch pack controller 68 allows hydraulic system information to be easily and conveniently displayed to the operator. Since present on the CAN bus 60, the data can be read by ESC 62, which uses the data in conjunction with engine speed data form the ECU 58 or transmission controller 64 to calculate rotational speed of and rotation count for barrel 110.
Referring now to
The invention provides improved reliability and reduced cost by elimination of conventional physical sensors used for monitoring barrel operation, and by estimating the required results by indirect means from existing data.
While the invention is shown in only one of its forms, it is not thus limited but is susceptible to various changes and modifications without departing from the spirit and scope of the invention.
