Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Construction or agricultural-type vehicle
Reexamination Certificate
2000-04-03
2002-01-01
Zanelli, Michael J. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Construction or agricultural-type vehicle
C037S414000
Reexamination Certificate
active
06336067
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a control unit for a construction machine, and more particularly to an electronic control system for a construction machine which includes a plurality of control units for controlling a prime mover, hydraulic equipment, a working device, a display unit, etc., and which interconnects the plurality of control units via a common communication line for transmission and reception of data.
BACKGROUND ART
Recently, with the advancement of electronic control incorporated in construction machines, particularly in a hydraulic excavator as a typical example thereof, the amount of computation to be processed by a control unit has increased more and more because of various kinds of computation required for the electronic control. The increased amount of computation necessitates the use of a high-performance microcomputer, and hence pushes up a cost. Also, the number of input/output signals is increased, which results in an increased number of wire harnesses. To overcome such a problem, dispersion of control units has been studied. In dispersion of control units, control functions of a hydraulic excavator are divided in units of function, control units are provided one for each of the unit functions, and the control units are interconnected via a network for performing control.
For example, JP, B, 7-113854 discloses an electronic control system for a hydraulic excavator wherein control units are provided one for each device, the control units for the respective devices are connected to a master controller via a common communication line, and integration of the overall system is maintained by the master controller.
Also, JP, B, 8-28911 discloses an electronic control system for a construction machine wherein control units are provided one for each device, and the control units are interconnected via a multi-transfer serial communication circuit to construct a network capable of two-way communication. This system is easily expandable.
Further, SAE Paper 941796 Development of Intelligent Hydraulic Excavator—HYPER GX Series (published in 1994) discloses an electronic control system for a hydraulic excavator wherein control units are provided one for each device, and the control units are interconnected via a network. The network is divided into a low-speed network and a high-speed network to ensure reliability of high-speed communication data and realize a cost reduction of the overall system.
DISCLOSURE OF THE INVENTION
In a hydraulic excavator as a typical example of construction machines, as mentioned above, electronic control has been advanced and various improvements have been achieved in points of control performance and production cost.
On the other hand, customer needs for hydraulic excavators have become diversified, for example, ranging from a demand for high-performance functions to a demand for an inexpensive machine.
In the electronic control system disclosed in JP, B, 7-113854, to satisfy the above customer needs, software of the master controller must be developed and changed, and the master controller must be replaced for each need. Moreover, with replacement of the master controller, software of the control unit provided for each device and connected to the master controller must be developed and changed, and the resultant software must be substituted for that of the existing control unit. Particularly, when high-performance functions are demanded, e.g., when automatic control functions such as operating area limitation and locus control are to be added to an excavating device of a hydraulic excavator, the kinds of software installed in the control units are increased. As a result, the number of steps for development and the development cost or management cost are increased.
On the contrary, when high-performance functions of a hydraulic excavator are not needed, software of the master controller and the control units must also be developed and changed correspondingly, and the resultant software must be substituted for the existing software. Therefore, the number of steps required for software development and the development cost are increased.
In the electronic control systems disclosed in JP, B, 8-28911 and SAE Paper 941796, the control units for the respective devices are interconnected via the network, and all signals to be transmitted and received among the control units can be transferred using the network. Accordingly, even when a number of signals are transmitted and received, it is not required to increase the number of signal lines. Also, even when a control unit having a new function is added to the system, there is no need of increasing the number of signal lines. Those electronic control systems are thus flexibly adaptable for system expansion.
In the case of adding a control unit for system expansion, there is no need of increasing the number of signal lines, but each control unit must be itself adapted for an increase in the number of signals (data) to be transmitted and received. In other words, the existing control units must be replaced and hence the cost is pushed up. Further, in the case of requiring not so high-performance functions and desiring to reduce the number of control units, each control unit must also be adapted for a decrease in the number of signals (data) to be transmitted and received. Such a case therefore similarly requires replacement of the existing control units. Further, in the case of replacing one of a plurality of control units by another unit upon change of a hydraulic system or a control system, if a particular one of the plurality of control units executes processing using a received signal and a control unit transmitting the received signal is replaced and excluded from the system, the particular control unit must also be replaced.
Additionally, when a multiplicity of control units transfer data among them via a network, the network would be too crowded to utilize necessary data on demand unless communication frequency is held at an optimum level. This results in a deterioration of the control performance of the control units.
A first object of the present invention is to provide an electronic control system and a control unit for a construction machine including a plurality of control units interconnected via a common communication line, wherein additional connection of a control unit to the common communication line and disconnection of any control unit from the common communication line can be performed without changing software in the existing control units and replacing the control units themselves, and system change including addition, exclusion and replacement of one ore more control units can be easily realized.
A second object of the present invention is to provide an electronic control system for a construction machine including a plurality of control units interconnected via a common communication line, wherein data communication frequency over a network is held at an optimum level and the control performance of the control units is avoided from deteriorating.
(1) To achieve the above first object, the present invention provides an electronic control system for a construction machine comprising a prime mover, a working device, and a hydraulic system for generating liquid pressure power by the prime mover and driving the working device, the construction machine further comprising a plurality of control units, the plurality of control units being interconnected via a common communication line to transmit and receive data, wherein at least one of the plurality of control units includes minimum processing means capable of executing least necessary processing by itself when no data is transmitted via the communication line.
With that feature of providing the minimum processing means in at least one control unit, in the case of reducing the number of control units, the least necessary processing can be performed by the minimum processing means even when no data is transmitted via the communication line. There is hence no need of changing software and replacing the control unit
Hitachi Construction Machinery Co. Ltd.
Mattingly Stanger & Malur, P.C.
Zanelli Michael J.
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