JPS6294622A - Controller for construction machine - Google Patents

Abstract

PURPOSE:To improve the fuel efficiency at small loads by a method in which at least one of the revolving number of an engine and the swash plate angle of a variable pump is controlled by a control signal to calculate the flow rate of pressure oil necessary for operations from the operation amounts of an operating lever for a working machine. CONSTITUTION:The operating amounts of an operating lever 1 is converted into an electric signal and put in a controller 2. A heavy load signal H, a standard load signal S, or a small load signal L from a load selecting switch 3 and a throttle signal from an accel pedal 4 are put in the controller 2. A map set up in the controller 2 is also sent out to an arithmetic circuit 7 to calculate a target revolving number Nr of an engine 6, a target rack position Rd, and a target swash plate angle thetad. These values so calculated are sent out to comparators 8, 9, and 10, respectively. The deviation DELTAN of revolving numbers is put in a swash plate angle correcting circuit 13 and sent out to the comparator 10, and the swash plate angle of a variable pump 5 is controlled by a variable pump control system 14. The occurrence of noise can thus be reduced.

Description

[Detailed Description of the Invention] Industrial Application Field This invention calculates the hydraulic flow rate required for work according to the amount of operation of a work equipment operating lever, and controls at least one of an engine and a variable pump with the obtained value. Related to control devices for construction machinery.

BACKGROUND OF THE INVENTION Conventional working machines of construction machinery are driven by the discharge pressure of a variable pump that is continuously operated by an engine, and the engine is operated at high speed during work. The output curve of the engine that drives the Mayu variable pump is set for each mode, and by controlling the absorption torque, the variable pump is matched at the high efficiency point of the engine, and the variable pump is operated ffi at the high efficiency side. The swash plate angle of the engine and variable pump was controlled in this way.

Problems to be Solved by the Invention However, with the above-mentioned conventional control device, the engine is used in a high-speed regulation range even when the load is low and the flow rate is low, resulting in poor fuel efficiency and the variable pump also has a small swash plate angle. Since the pump is used in a wide range of areas, there are disadvantages such as poor pump efficiency.This invention was made with the aim of improving the above-mentioned disadvantages.

Means and action for solving the problem The hydraulic flow rate required for the work is calculated from the operation amount of the work equipment control lever, and the obtained control signal is used to control the engine rotation speed and the tilt of the variable pump driven by the engine. A control device for construction machinery that improves fuel efficiency and reduces noise during light loads and low vL amounts by controlling at least one of the plate angles.

Embodiment An embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram of a control system, and numeral 1 indicates a control lever of a working machine installed on a construction machine (not shown). The operation t of the operating lever 1 is converted into an electrical signal and input to the controller 2. The controller 2 receives a load selection switch 3, a load signal H1, a standard load signal S, a light load signal, and a throttle signal from an accelerator pedal 4. Three types of maps are stored in advance in the manual controller 2. One is a PQ left curve that shows the relationship between the discharge pressure P of the variable pump 5 and the flow iQ, which will be described later.The other is a target engine map that shows the relationship between the rotation speed N and torque T of the engine 6, and one is a target pump map. According to the input signal, the engine map is set to a high efficiency range on the low rotation side, and the pump map is set to a high efficiency range on the high rotation angle side. The map set by the controller 2 is output to the map hug@road 7, and the target rotation speed Nr of the engine 6 and the target angle θd of the engine 6 are calculated from these maps, and the comparator &
,9. Output to. The output rotation Ne of the engine 6 is fed back to the comparator 8 to which the target rotation speed pJr is input, and the deviation jN between the target rotation speed Nr and the actual rotation speed Ne is calculated, and this deviation N is used for rack position correction. is input to the circuit 11 and set in advance. A rack position correction signal ΔR is calculated from the map shown in FIG. Rd is added to the rack position command signal RC,
It is output to the fuel injection pump control system 12. Fuel injection pump control system +21-t, input rank position command signal R
1? Depending on the engine 6 fuel injection pump (not shown)
control.

On the other hand, the rotation speed deviation ΔN is also input to the swash plate angle correction circuit 13, and a swash plate angle correction value lθ is calculated according to the preset map deviation ΔN.
is output to the comparator 10 to which is input. Comparator 10
is the swash plate angle correction signal lθ. :A The swash plate angle θd is added to obtain the swash plate angle command signal θC, which is output to the variable pump control system 14. The variable pump control system 14 controls the swash plate angle of the variable pump 5 according to the input swash plate angle command signal 0C, so that the engine 6 and the variable pump 5 are matched at a predetermined operating point. As it becomes,
The discharge pressure of the variable pump 5 is supplied to a working machine (not shown), and a portion is fed back to the arithmetic circuit 7 as the discharge pressure pc.

Next, to explain the operation, in order to select light load S using the load selection switch 3 and perform work, the work equipment operating lever 1
111: When operated from the neutral position to a position of approximately 70% (relative to the total amount of operation), the matching points that were at the second two points at neutral position move to the point at 70% operation, and matching is performed at this point. It's like doing that. On the other hand, in the conventional control device, matching is performed at point C when neutral, and the matching point is at the second [9
The engine moves to point d and matches, and compared to the conventional control method described above, the engine speed can be sufficiently reduced to 60 rpm when in neutral, and during work, the output torque can be varied with an even greater output torque than the conventional control method. The pump 5 can be driven, thereby improving fuel efficiency and reducing noise during work.

On the other hand, the neutral variable pump 5 of the work equipment operating lever 1 is driven by the 4 points of the third factor, and when the operating lever 1 is operated to the 70% position, the operating point moves from 4 points to 1 point and is matched. be done. On the other hand, in the conventional system, matching is performed at the same point f, and the efficiency of the variable pump 5 driven by the larger swash plate angle is also improved compared to the conventional system.

In the above embodiment, the rank position of the fuel injection pump and the swash plate angle of the variable pump 5 are controlled in accordance with the rotational speed deviation ΔN, and the effect can be obtained even if either one is controlled. be.

Further, FIGS. 4 and 5 show redundant circuits of an engine employing a Seiko governor, which will be explained next.

The 20th anniversary of the death was a Kameko governor 20cLtW engine.
The variable pump 21 is driven, and the engine 200 rotation speed Ng is input to the control system 22. The control system 22 is provided with a controller 23 in which a map similar to that of the previous embodiment is set, and the target rotation speed Nr and target torque variable control signal Ad are sent from the controller 23 to comparators 24 and 25, respectively. It's outputting. The comparator 24 has the engine 200
The rotation speed Ng is input, and the deviation ΔN from the target rotation speed Nr is calculated. This deviation ΔN is input to the current correction circuit 26, and the current correction value ΔA is calculated from a preset map. This current correction value ΔA is output to the comparator 25 and added to the target torque variable control signal Aet, and the command '
The current becomes AC. This command current A(?) is output to the variable torque control valve 27, and the variable pump 21 is controlled as follows.

That is, the discharge pressure 2) is fed back to the variable torque control valve 27, and the target rotation speed Nr is fed back to the engine 20.
When the output rotation speed increases, control pressure is discharged to the servo mechanism 21α so that the swash plate angle of the variable pump 21 increases. As a result, the hydraulic load exceeds the engine torque, so the rotational speed of the engine 20 decreases.

Conversely, when the output rotational speed of the engine 20 decreases, the pump swash plate angle becomes smaller, and the hydraulic load becomes lower than the engine torque, so the rotational speed of the engine 20 increases. In this way, even when the redundant circuit is selected by a changeover switch (not shown), appropriate matching can be obtained, thereby preventing engine 20 overrun or stalling even if the rack position of the fuel injection bonder is fixed. You will be able to do this.

Note that instead of the variable torque control valve 27, a pressure sensor is provided to detect the discharge pressure of the variable pump 2I, and a control amount is calculated by a microcomputer based on the detected value of this pressure sensor, and the variable pump 21 is controlled. Good too.

Furthermore, when the work equipment actuator pressure is low, even if the swash plate angle of the variable pump 21 is maximized, the hydraulic load may be small and the engine speed may further increase to 200 rpm.In such cases, the opening degree of the work equipment control valve may be reduced. It is also possible to prevent the engine 2o from overrunning by increasing the hydraulic load by causing a pressure loss.

The effect of the above embodiment is that even if the solenoid of the controller 23, the electronic governor 20α, or the rank position detector fails, by selecting a redundant circuit, it is possible to continue the work. It can prevent the engine from stalling or running during the engine.

Effects of the Invention As described in detail above, this invention calculates the hydraulic flow 1i required for work according to the amount of operation of the work equipment operating lever, and uses the obtained ratio control signal to control the rotation of the engine and the swash plate of the variable pump. Since at least one of the corners is controlled, light loads can be achieved.
When working at low flow rates, fuel efficiency can be improved and noise generation can also be reduced.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention; FIG. 1 is a block diagram, FIGS. 2 and 3 are action explanatory diagrams, and FIGS. 4 and 5 are explanations showing other embodiments. 1 is a work equipment operating lever, 5 is a variable pump, and 6 is an engine.

Claims (1)

[Claims] The hydraulic flow rate required for the work is calculated from the operation amount of the work equipment operating lever 1, and the obtained control signal controls at least one of the rotation speed of the engine 6 and the swash plate angle of the variable pump 5 driven by the engine 6. A control device for construction machinery characterized by: