JP4705598B2 - Engine speed control device for construction machinery - Google Patents

Description

  The present invention relates to an engine speed control device for a construction machine, and more particularly to an engine speed control device for a construction machine that prevents engine stall when the engine speed is low.

  In recent years, this type of construction machine includes an engine control unit that adjusts the injection amount and injection timing of an electronically controlled fuel injection pump, and sends a command signal from the controller for main body control to the engine control unit to A configuration for controlling the above is known. In order to save energy, when the machine is not operating, the engine speed is often reduced to the minimum speed by operating the throttle volume or the one-touch idle switch.

  For example, a low rotation speed command means, a non-operation state detection means, a position detection sensor, a work interruption state detection means, and a switching output means are provided to detect that a steering operation or a work machine operation operation is interrupted. In such a case, a device is known that switches to the rotation command from the low rotation speed command means and automatically controls the engine so that the minimum allowable engine speed is lower than the low idle rotation speed (see Patent Document 1).

Further, in a construction machine having an auto idle function that automatically reduces the engine speed when the work machine is not operating, the controller stores a predetermined speed in a stable region where the engine does not cause hunting or engine stall. When the work implement is not operating and the engine is operating at a lower speed than the predetermined speed, and the engine is loaded by the start of the work implement operation, the engine speed is controlled by the speed signal output from the controller. There is also known an apparatus that automatically controls an operating part for controlling the device so that the engine speed is increased to a predetermined speed or higher (Patent Document 2).
Japanese Patent No. 2567220 Japanese Patent No. 3580941

  The invention described in Patent Document 1 improves the fuel consumption by switching the engine speed to a lower rotational speed than the low idle rotational speed when the driving operation of the aircraft or the driving operation of the work machine is interrupted. The engine noise is reduced, but when the work interruption state is switched to the work state, a signal indicating the work state is output from the timer constituting the work interruption state detection circuit, and the engine speed is set to the target rotation speed. Therefore, when all of the multiple sensors are not operated, the work is interrupted, and when any one of the multiple sensors is operated, the work is performed, regardless of the engine load factor. However, since the engine speed always increases and the engine speed is increased even in operations that do not cause the engine stall, the fuel consumption deteriorates and the noise also increases. There was a case.

  Further, in the detailed description of the invention of Patent Document 2 and FIG. 3, the value indicated by the engine speed indicator is smaller than a predetermined speed N that does not cause hunting or engine stall, and the operation lever is ON, that is, the operation When the engine speed is in a state, the engine speed is set to a predetermined speed N. When the indicated value is smaller than the predetermined speed N and the operation lever is OFF, that is, in the non-operating state, the engine speed is set to a predetermined speed. On the other hand, when the indicated value is equal to or higher than the predetermined rotational speed N, the engine rotational speed is set to the indicated value, that is, the predetermined value regardless of whether the operation lever is ON or OFF, that is, the operating state or the non-operating state. A technique for making the number of revolutions N or more is disclosed. Of these, the invention according to claim 1 of Patent Document 2 is such that the indication value input by the revolution number indicator is smaller than a predetermined number of revolutions N and the operation is performed. Les When the engine is ON, that is, in the operating state, the engine speed is increased to a predetermined rotational speed N or more, and it is detected whether the operation lever is ON, that is, whether it is in the operating state, and the engine load factor is detected. Therefore, there is a problem similar to that of Patent Document 1. Further, claims 2 and 3 of Patent Document 2 are modifications of Claim 1, and the inventions of Claims 2 and 3 have the same problems as Patent Document 1.

  Therefore, when the engine speed is lower than the predetermined speed, the engine load factor is used to predict the occurrence of engine stall, and if there is a possibility of engine stall, the engine speed is automatically increased. The technical problem which should be solved arises, and this invention aims at solving this problem.

The present invention has been proposed in order to achieve the above object, and the invention according to claim 1 is an engine control unit for adjusting an injection amount and an injection timing of a fuel injection pump, and can communicate with the engine control unit. An engine speed control device for a construction machine comprising a main body controller for controlling the engine control unit connected to the engine control unit ,
Whether the controller receives an engine load factor signal from the engine control unit when the engine speed is lower than a predetermined idle speed at which engine stall does not occur , and whether to increase the engine speed based on the change in the engine load factor In the engine speed control device for a construction machine designed to determine
The controller is provided with engine load factor determining means, and when the engine load factor calculated by the engine control unit is transmitted by the controller via CAN communication, the engine load factor determining means When it is determined whether or not the engine load factor exceeds a certain value, a signal for increasing the engine speed is transmitted by CAN communication from the controller to the engine control unit. The control unit performs control so that the engine speed operation is performed based on the transmitted engine speed increase signal ,
On the other hand, if the controller determines that the engine speed is equal to or higher than the predetermined engine speed that does not cause the engine stall , or if the received engine load factor does not exceed the predetermined value , the controller An engine speed signal set by the throttle volume is transmitted by CAN communication from the engine to the engine control unit, and the engine speed operation is performed based on the engine speed signal by the throttle volume transmitted by the engine control unit. Provided is an engine speed control device for a construction machine, which is characterized by control.

  According to this configuration, when the engine speed is lower than the predetermined speed, the rack displacement amount is detected by the sensor to calculate the engine load factor, and the engine load factor is transmitted to the controller. The controller determines whether to increase the engine speed based on the received change in the engine load factor. If it determines that the engine speed does not need to be increased, the controller keeps the engine speed low while rotating to prevent engine stall. When it is determined that the engine needs to be increased, the engine speed is controlled to increase.

  According to this configuration, the controller monitors the engine load factor signal sent from the engine control unit via CAN communication, the engine load factor causes a predetermined change, and increases the engine speed. When it is determined that the engine speed needs to be increased, a signal for increasing the engine speed is transmitted to the engine control unit by CAN communication. This increases the engine speed and prevents engine stall.

  In the present invention, the controller predicts the occurrence of engine stall based on the engine load factor sent from the engine control unit and determines an increase in the engine speed. If the torque is sufficient, the engine speed is not increased. Accordingly, it is possible to prevent deterioration of fuel consumption due to useless high rotation. On the other hand, even when there is no work operation, when the engine load factor increases, the engine speed is increased, so that an unexpected engine stall can be prevented.

  Thus, when the engine speed is lower than the predetermined speed, the engine speed can be increased as necessary to prevent engine stall, and when not required, the engine speed can be kept low to improve fuel efficiency. Can do.

  Hereinafter, the engine speed control device for a construction machine according to the present invention will be described with reference to preferred embodiments. Achieving the purpose of predicting engine stall from the engine load factor when the engine speed is lower than the specified engine speed, and automatically increasing the engine speed if there is a possibility of engine stall Therefore, the present invention provides an engine speed control device for a construction machine comprising an engine control unit that adjusts an injection amount and an injection timing of a fuel injection pump, and a main body control controller that controls the engine control unit. When the engine speed is lower than the predetermined engine speed, the controller receives an engine load factor signal from the engine control unit, and determines whether to increase the engine engine speed based on the change in the engine load factor.

  FIG. 1 shows an engine speed control circuit in a hydraulic excavator as an example of a construction machine, an engine 10, an engine control unit 11 that adjusts the injection amount and timing of a fuel injection pump and detects the engine speed, and an engine 10. The hydraulic pump 13 is driven by the pump to pump up and discharge the hydraulic oil in the hydraulic oil tank 12, the direction control valve 14 that controls the direction and flow rate of the hydraulic oil discharged from the hydraulic pump 13, and the direction control valve 14 The actuator 15 is provided with hydraulic oil supplied and discharged via the shaft to drive the work implement.

  Reference numeral 16 denotes a driving operation detection sensor for the work machine, which detects movements of various operation levers such as a boom, an arm, or traveling, or is operated hydraulic pressure supplied to the actuator 15 by switching one of the directional control valves 14. , And the presence or absence of a traveling operation of the machine body or a driving operation of the work machine is detected based on a change in stroke or pressure. Reference numeral 17 denotes a pressure detection sensor that detects the discharge pressure of the hydraulic pump 13, the negative control pressure of the center bypass, and the like. Detection signals from these detection sensors 16 and 17 are transmitted to a controller 20 for controlling the main body, and a throttle volume 18 is connected to the controller 20.

  The controller 20 performs various controls of the operation of the main body. In the control related to the engine 10, the engine speed is set by various detection signals including the driving operation detection sensor 16 and setting signals by the throttle volume 18 and the like. While determining and transmitting a command signal to the engine control unit 11 by CAN communication, the actual engine speed detected by the engine control unit is received and compared with a stored predetermined engine speed, Make a decision.

  When the engine control unit 11 receives an engine speed command signal from the controller 20 through CAN communication, the engine control unit 11 adjusts the injection amount and the injection timing of the fuel injection pump so that the engine speed is based on the command signal. . Further, the amount of rack displacement is detected by a sensor to calculate an engine load factor, and this engine load factor is transmitted to the controller 20 by CAN communication.

  Further, the controller 20 is provided with an engine load factor determination means 21 for determining whether or not to increase the engine speed based on the received change in the engine load factor. Based on this determination, the controller 20 controls the engine. A command signal is transmitted to the unit 11. Further, the controller 20 sends a control signal to the pump regulator 22 as necessary to adjust the tilt angle of the hydraulic pump 13 and change the pump discharge amount.

  FIG. 2 is a flowchart of engine speed control. First, the engine 10 is started (step 1), and the engine speed is set by the throttle volume 18 (step 2). Then, the controller 20 determines whether or not the engine speed detected by the engine control unit 11 is lower than a predetermined speed at which engine stall does not occur (step 3).

  If the engine load factor calculated by the engine control unit 11 is transmitted to the controller 20 by CAN communication when the engine speed determined by the controller 20 is lower than the predetermined engine speed, the engine load factor provided in the controller 20 The determination means 21 determines whether or not a predetermined change has occurred, such as whether the engine load factor has exceeded a certain value or has suddenly increased due to a change exceeding a certain inclination (step 4).

  If it is determined that the received engine load factor has undergone a predetermined change, it is further determined whether the engine speed needs to be increased (step 5), and it is determined that the engine speed needs to be increased. The controller 20 transmits a command signal for increasing the engine speed to the engine control unit 11 by CAN communication. The engine control unit 11 in accordance with the command signal from the controller 20 injects the injection amount and the injection timing of the fuel injection pump. The engine speed is increased to a speed at which engine stall is unlikely to occur (step 6 and step 7), and the process proceeds to the next step.

  On the other hand, if it is determined in step 3 that the engine speed is equal to or higher than the predetermined speed, or if it is determined that the engine load factor received in step 4 does not cause a predetermined change, step 5 is further performed. If it is determined that there is no need to increase the engine speed, the engine speed operation set by the throttle volume 18 is performed (step 8), and the process proceeds to the next step.

  As described above, engine stall can be prevented by increasing the engine speed as required from changes in the engine load factor, and when not required, the engine speed can be kept low to improve fuel efficiency.

  It should be noted that the present invention can be variously modified without departing from the spirit of the present invention, and the present invention naturally extends to the modified ones.

The circuit diagram of the engine speed control apparatus which concerns on this invention. The flowchart of the engine speed control which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Engine 11 Engine control part 12 Hydraulic oil tank 13 Hydraulic pump 14 Direction control valve 15 Actuator 16 Operation detection sensor 17 Pressure detection sensor 18 Throttle volume 20 Controller 21 Engine load factor determination means 22 Pump regulator

Claims (1)

An engine speed control device for a construction machine, comprising: an engine control unit that adjusts an injection amount and an injection timing of a fuel injection pump; and a main body control controller that is connected to the engine control unit so as to be able to perform CAN communication and controls the engine control unit Because
Whether the controller receives an engine load factor signal from the engine control unit when the engine speed is lower than a predetermined idle speed at which engine stall does not occur , and whether to increase the engine speed based on the change in the engine load factor In the engine speed control device for a construction machine designed to determine
The controller is provided with engine load factor determining means, and when the engine load factor calculated by the engine control unit is transmitted by the controller via CAN communication, the engine load factor determining means When it is determined whether or not the engine load factor exceeds a certain value, a signal for increasing the engine speed is transmitted by CAN communication from the controller to the engine control unit. The control unit performs control so that the engine speed operation is performed based on the transmitted engine speed increase signal ,
On the other hand, if the controller determines that the engine speed is equal to or higher than the predetermined engine speed that does not cause the engine stall , or if the received engine load factor does not exceed the predetermined value , the controller An engine speed signal set by the throttle volume is transmitted by CAN communication from the engine to the engine control unit, and the engine speed operation is performed based on the engine speed signal by the throttle volume transmitted by the engine control unit. An engine rotation speed control device for a construction machine, characterized by controlling.