JP4973620B2 - Construction machine control equipment - Google Patents

Description

  The present invention relates to a control device for regenerating an exhaust gas filter and preventing engine overheating in a construction machine such as a hydraulic excavator.

  Conventionally, exhaust gas discharged from a diesel engine is introduced into an exhaust gas filter (DPF: Diesel Particulate Filter) to remove harmful substances, especially PM (Particulate Matter: Particulate Matter; explained in this example below) such as soot. An exhaust gas purification device for purification is known (see Patent Document 1).

  In this type of exhaust gas purification device, in order to keep the purification function of the exhaust gas filter constant, filter regeneration (self-regeneration) that burns and removes PM deposited on the exhaust gas filter when the amount of PM deposition exceeds a certain level Also called).

  This filter regeneration is performed, for example, by fuel injection control by the control means, that is, by additionally injecting fuel on the engine side and heating the exhaust gas (usually heating the exhaust gas at 150 to 250 ° C. to 350 to 600 ° C.). Is called.

On the other hand, in a construction machine such as a hydraulic excavator that performs constant horsepower control, an output of a hydraulic pump that is a hydraulic source of a hydraulic actuator (for example, when the temperature of engine cooling water exceeds a set value as a precursor of engine overheating ( By performing the horsepower reduction control that reduces the pump discharge amount), the engine load is reduced to prevent overheating.
JP-A-5-26035

  However, filter regeneration is control for increasing the exhaust gas temperature, while horsepower reduction control for preventing overheating is a conflicting control that lowers the exhaust gas temperature by reducing the engine load.

  For this reason, when the horsepower reduction control is executed during filter regeneration, or vice versa, that is, when filter regeneration and horsepower reduction control are performed simultaneously, the exhaust gas temperature falls and filter regeneration is interrupted or disabled. The problem of becoming occurred.

  Accordingly, the present invention provides a construction machine control device capable of achieving both of the functions of filter regeneration and overheating prevention.

The invention of claim 1 comprises an engine, a hydraulic pump as a hydraulic source of a hydraulic actuator, an exhaust gas filter for removing harmful substances in the exhaust gas emitted from the engine, and a control means for controlling the engine and the hydraulic pump. This control means
(A) Preventing overheating by performing horsepower reduction control that reduces the output of the hydraulic pump based on a signal from a sensor that monitors engine overheating;
(B) Perform filter regeneration control to regenerate the exhaust gas filter by incinerating harmful substances by heating the exhaust gas,
(C) When the horsepower reduction control and the filter regeneration control are performed at the same time, the reduction degree of the horsepower is limited so that the horsepower can prevent the engine overheating while maintaining the exhaust gas temperature capable of maintaining the filter regeneration action. It is configured to perform horsepower reduction control.

  According to a second aspect of the present invention, there is provided an exhaust gas temperature sensor for detecting a temperature of the exhaust gas emitted from the engine in the configuration of the first aspect, and the control means detects the exhaust gas temperature by the exhaust gas temperature detected by the exhaust gas temperature sensor. The horsepower reduction control is configured on the condition that the temperature suitable for performing is equal to or higher than a preset value.

  According to the present invention, when the horsepower reduction control and the filter regeneration control are performed simultaneously, the degree of decrease in horsepower (specifically, the degree of decrease in pump discharge amount) is limited, and the exhaust gas temperature that can maintain the filter regeneration action is set. Since the control is performed so that the horsepower can prevent overheating of the engine while maintaining, a decrease in exhaust gas temperature due to the horsepower reduction control can be suppressed.

  That is, it is possible to achieve both functions that conflict with each other in terms of exhaust gas temperature, such as filter regeneration and prevention of overheating.

  According to the second aspect of the present invention, since the reduction of the horsepower is not started simultaneously with the start of the filter regeneration operation, but the reduction of the horsepower starts only when the exhaust gas temperature rises above the temperature suitable for the filter regeneration. The regenerative action can be reliably maintained.

  In the construction machine according to the embodiment, as shown in FIG. 1, a variable displacement hydraulic pump 2 is driven by an engine 1, and oil discharged from the hydraulic pump 2 is supplied to a plurality of hydraulic actuators (here, one hydraulic actuator). Supplied as 4).

  The discharge amount (tilt) of the hydraulic pump 2 is controlled through the pump regulator 5 by a controller 5 as control means so that the horsepower is always constant. That is, constant horsepower control is performed as basic control.

  On the other hand, an exhaust gas filter 8 is provided in the exhaust passage 7 for releasing the exhaust gas from the engine 1 to the outside, and PM in the exhaust gas is removed by the exhaust gas filter 8.

  In addition to the above-described constant horsepower control, the controller 5 performs a horsepower reduction control for preventing overheating of the engine 1 and a filter regeneration for incinerating the PM accumulated in the filter 8 to keep the purification action of the exhaust gas filter 8 constant. Control.

  As sensors for obtaining information for starting both of these controls, a cooling water temperature sensor 9 for detecting the cooling water temperature of the engine 1, an accumulation amount sensor 10 for detecting the PM accumulation amount of the exhaust gas filter 8, and an output from the engine 1. The exhaust gas temperature sensor 11 for detecting the temperature of the exhaust gas is provided, and signals from the sensors 9 to 11 are sent to the controller 5.

  As overheat prevention control, the controller 5 detects a value Ts of the engine coolant temperature based on a signal from the coolant temperature sensor 9, and a detected value Ts that is set in advance as a precursor to overheating (a temperature that causes overheating if left untreated) T1 or more. Then, the horsepower reduction control is performed through the pump regulator 6 so that the output of the hydraulic pump 2 becomes a value calculated from the engine coolant temperature / pump output table (a value smaller than the pump output at that time). Specifically, the pump tilt is changed so that the discharge amount decreases.

  This horsepower reduction control reduces the engine load and prevents overheating.

  On the other hand, as the filter regeneration control, when the PM accumulation amount becomes equal to or more than a preset value as a limit value that can maintain the desired exhaust gas purification action, for example, based on the signal from the accumulation sensor 10, the engine 5 Filter regeneration control is performed in which post fuel injection is performed to heat the exhaust gas and the accumulated PM is incinerated.

  By this filter regeneration control, the exhaust gas purification action of the exhaust gas filter 8 is maintained.

  Further, when the horsepower reduction control and the filter regeneration control for the hydraulic pump 2 are performed at the same time, the controller 5 performs horsepower reduction control for limiting the degree of horsepower reduction. The operation of this point will be described with reference to the flowchart of FIG.

  In step S1, it is determined whether or not the detected engine coolant temperature is equal to or higher than the set value T1, and if YES, the horsepower control according to the coolant temperature is performed on the hydraulic pump 2 as described above (step S2). ).

  In step S3, it is determined whether the filter is being regenerated. If NO, the process returns to step S1, and if YES, the process proceeds to step S4.

  In step S4, it is determined whether or not the exhaust gas temperature detected by the exhaust gas temperature sensor 11 has risen to a set value T2 (a temperature suitable for performing filter regeneration) or more. If NO, the process returns to step S3. When YES, horsepower reduction control is performed in step S5.

  That is, control is performed to suppress the degree of decrease in horsepower so that the horsepower can prevent overheating of the engine 1 while maintaining the exhaust gas temperature that can maintain the filter regeneration action.

  This horsepower reduction control is performed until the filter regeneration is completed (YES in step S6), and thereafter, the control is stopped in step S7 and the original horsepower reduction control without limitation is returned.

  As described above, when the horsepower reduction control and the filter regeneration control are simultaneously performed, the reduction degree of the horsepower (specifically, the degree of reduction of the pump discharge amount) is limited, so that the reduction of the exhaust gas temperature due to the horsepower reduction control is suppressed. be able to.

  That is, it is possible to achieve both functions that conflict with each other in terms of exhaust gas temperature, such as filter regeneration and prevention of overheating.

  In addition, since the horsepower reduction is not started simultaneously with the start of the filter regeneration action, the horsepower reduction is started only when the exhaust gas temperature rises to a temperature T2 or higher suitable for filter regeneration by the processing in steps S3 to S5. The filter regeneration operation can be reliably maintained.

Other Embodiments (1) In the above embodiment, the case where filter regeneration is performed based on the PM accumulation amount of the exhaust gas filter 8 is taken as an example. However, the present invention performs filter regeneration periodically or at regular intervals of operation time. It can also be applied to the case where

  (2) In the above embodiment, the overheat of the engine 1 is monitored by the cooling water temperature. However, another overheat index (engine temperature or the like) may be monitored.

It is a schematic block diagram around an engine and a pump showing an embodiment of the present invention. It is a flowchart for demonstrating the effect | action of embodiment.

Explanation of symbols

1 Engine 2 Hydraulic pump 4 Hydraulic actuator 5 Controller (control means)
6 Pump regulator 7 Exhaust passage 8 Exhaust gas filter 9 Cooling water temperature sensor 10 Accumulated amount sensor 11 Exhaust gas temperature sensor

Claims (2)

An engine, a hydraulic pump as a hydraulic source of a hydraulic actuator, an exhaust gas filter for removing harmful substances in the exhaust gas emitted from the engine, and a control means for controlling the engine and the hydraulic pump,
(A) Preventing overheating by performing horsepower reduction control that reduces the output of the hydraulic pump based on a signal from a sensor that monitors engine overheating;
(B) Perform filter regeneration control to regenerate the exhaust gas filter by incinerating harmful substances by heating the exhaust gas,
(C) When the horsepower reduction control and the filter regeneration control are performed at the same time, the reduction degree of the horsepower is limited so that the horsepower can prevent the engine overheating while maintaining the exhaust gas temperature capable of maintaining the filter regeneration action. A construction machine control device configured to perform a horsepower reduction control.   An exhaust gas temperature sensor for detecting the temperature of the exhaust gas emitted from the engine is provided, and the control means is configured so that the exhaust gas temperature detected by the exhaust gas temperature sensor is not less than a preset value as a temperature suitable for regenerating the exhaust gas filter. The construction machine control device according to claim 1, wherein the control device is configured to perform a horsepower reduction control on condition that there is a certain condition.

Images