JPH02167935A - Prime mover rotation speed control device for hydraulic construction machinery - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a prime mover rotational speed control device for hydraulic construction machinery.

B. Conventional technology Hydraulic construction machinery drives multiple hydraulic actuators using oil discharged from a hydraulic pump driven by an engine, and each hydraulic actuator is controlled by an operating member such as an operating lever or an operating pedal. Driven individually or simultaneously.

Japanese Patent Publication No. 60-38561 discloses the following engine rotation speed control method aimed at improving the fuel efficiency and reducing noise of this type of hydraulic construction machinery. In other words, the measurement of a predetermined time (delay time) is started after all the operation members mentioned above are in the neutral state, and if all the operation members are not operated during the time measurement, the set engine rotation will start after this delay time has passed. The engine, which is currently rotating at a predetermined low rotation speed (hereinafter referred to as a set engine rotation speed), is operated by lowering the rotation speed to a predetermined low rotation speed. In this specification, this engine rotation speed control is referred to as low-speed operation control. Note that the set engine speed is set by a set engine speed command operating member such as a fuel lever located in the driver's seat.

According to this, when all operating members are in a neutral state, such as during a short break from one work, the engine speed is automatically lowered, thereby improving fuel efficiency and reducing noise and electricity.

￥lAM that the C0 invention aims to solve By the way, in such low-speed controlled driving, fuel consumption,
From the viewpoint of noise and the like, it is preferable to lower the engine speed to the lowest possible speed. However, if the set engine speed is relatively high, lowering the engine speed to a sufficiently low speed will cause a first-order problem.

■When the engine speed returns to the set engine speed from a low speed, black smoke is emitted, which is unfavorable in terms of engine durability and exhaust gas countermeasures.

■The engine speed fluctuates greatly and is annoying.

■If the engine speed fluctuates greatly, the energy used to accelerate the engine flywheel is lost, resulting in poor fuel efficiency.

Therefore, when the set engine speed is relatively high, the above-mentioned delay time is lengthened to avoid frequent low-speed engine operation control.

For example, when all the operating members happen to be in a neutral state during work, it is desirable to prevent undesired low-speed operation control from being performed. On the other hand, when the set engine speed is low, the above mentioned ■■■ does not pose much of a problem, so in order to improve fuel efficiency, the delay time described above is shortened and low-speed operation control is performed frequently. It is desirable to do so.

However, in the conventional device described above, since this delay time is fixed, it is not possible to set the delay time to an appropriate value depending on the level of the set rotation speed.

The technical problem of the present invention is to change the above-mentioned delay time in accordance with the set rotational speed.

06 Means for Solving the Problems To explain with reference to FIG. 1, which is a diagram corresponding to the claims, the present invention comprises a hydraulic pump 101 driven by a prime mover 100, and at least one hydraulic pump driven by pressure oil discharged from the hydraulic pump 101. one hydraulic actuator 102;
Valve means 10 for controlling operation of hydraulic actuator 102
3, an operating means 104 that is provided corresponding to the hydraulic actuator 102 and controls the operation of the hydraulic actuator by operating the valve means 103; a set rotation speed command means 105 that arbitrarily commands the set rotation speed of the prime mover; The present invention is applied to a hydraulic construction machine including a prime mover control means 106 that controls the prime mover 100 so that the set rotation speed is set.

The above-mentioned technical problem is solved by the first-order configuration. A detection means 107 detects whether or not the operation means 104 is in a neutral state, and based on the detection result from the detection means 106, it is determined whether at least one of the operation means 104 is in the operation position or all of them are in the neutral position. a determining means 108 that determines whether the operating means 104 is in the neutral position; a timing means 109 that starts counting when the determining means 108 determines that all of the operating means 104 are in the neutral position; and a set rotation speed commanding means. A calculating means 110 is provided for calculating a delay time corresponding to the set rotational speed, which becomes longer as the set rotational speed is higher.

Furthermore, the prime mover control means 106 controls the prime mover rotation speed as follows.

■When the determination means 108 determines that at least one of the operating means 104 is being operated, the driving force @ is set at the set rotation speed commanded by the set rotation speed command means 105.
100 is driven.

■When the determining means 108 determines that all of the operating means 104 are in the neutral state, the time measuring means 1
When 09 times the delay time calculated by the calculation means 110, the prime mover 10 starts running at a low rotation speed lower than the set rotation speed.
0 is driven.

81 action calculating means 110 calculates a delay time corresponding to the set rotation speed. This delay time becomes longer as the set rotation speed is higher. When all of the operating means 104 are in the neutral state, the prime mover control means 106 operates the prime mover 100 at a low rotation speed lower than the set rotation speed after the calculated delay time has elapsed. As a result, the lower the set rotation speed, the more frequently the low-speed operation control is performed.

F. Embodiment An embodiment in which the present invention is applied to a wheeled hydraulic excavator will be described based on FIGS. 2 and 3.

FIG. 2 is a diagram showing a hydraulic circuit and a control circuit in which the present invention is applied to a wheeled hydraulic excavator.

In FIG. 2, pressure oil discharged from a hydraulic pump 1 driven by an engine (prime mover) 21 has its direction and flow rate controlled by a hydraulic pilot type control valve (valve means) 2, and passes through a counterbalance valve 3. It is supplied to the hydraulic motor 4.

The stroke amount of the pilot type control valve 2 is controlled by pilot pressure from a pilot hydraulic circuit. The pilot hydraulic circuit includes a pilot hydraulic pump 5 and a pilot valve 6 (these are operating means) linked to a travel pedal 6a, and controls the stroke amount of the control valve 2 by pressure oil from the pilot valve 6. to control the vehicle's running speed. Further, a slow return valve 7 follows the pilot valve 6 and delays the return of oil to the pilot valve 6, and a slow return valve 7 follows the slow return valve 7 to delay the return of oil to the pilot valve 6.

A forward/reverse switching valve 8 for selecting reverse or neutral is provided. The oil discharged from the hydraulic pump 5 is transferred to these pilot valves 6. Pilot boat 2a or 2b of pilot type control valve 2 via slow return valve 79 forward/reverse switching valve 8
This causes the control valve 2 to switch at a stroke amount depending on the oil pressure.

When the control valve 2 returns to the neutral position, a delay time is provided by the slow return valve 7. Furthermore, a check valve 18a is provided in the input/output line of the hydraulic motor 4.

A makeup line 19 is connected via 18b, and makeup oil is supplied from the pilot hydraulic pump 5.
This is intended to prevent cavitation.

The driving force of the hydraulic motor 4 is transmitted to a transmission via an output shaft (not shown), and further rotates the wheels via a propeller shaft to cause the vehicle to travel.

The above is the configuration of the running system.

On the other hand, a working pilot type control valve 11 is provided in tandem downstream of the driving control valve 2, and a working actuator 12 is driven and controlled by this control valve 11. control valve 1
1 is switched by rotating the operating lever 13a of the pilot valve 13. Furthermore, a hydraulic pump 14 driven by an engine 21 is provided, and a working actuator 16 is connected to this hydraulic pump 14 via a working pilot type control valve 15 . The control valve 15 is also switched by rotating the operating lever 17a of the pilot valve 17.

In the device configured as described above, a running travel pedal 6a and working operating levers 13a and 17a are provided as operating members, and the operating state of each operating member is detected. Detection of whether the travel pedal 6a is in a neutral state is performed by a pressure switch 31 that detects the line pressure between the travel control valve 2 and the operating hydraulic pump 5. Detection of whether the work operation levers 13a, 17a are in a neutral state is as follows.

This is done by limit switches 32 and 33 that are linked to the operating levers 13a and 17a and are turned on only in the neutral position. These switches are the detection means.

Next, the rotation speed control device for the engine 21 will be explained. The rotation speed of the engine 21 is set to I by the governor 21a.
Six governors 21a controlled by eleven controllers are connected to a pulse motor 23 by a link mechanism 22.

It is driven according to the rotation of the pulse motor 23 to control the engine rotation speed. A potentiometer 25 is connected to the pulse motor 23 by a link mechanism 24, and the rotational position of the pulse motor 23 is detected by the potentiometer 25 as a governor lever position detection value, which will be described later. The rotation of the pulse motor 23 is controlled by a motor drive signal from a control circuit 30. Here, the governor 21a and the control circuit 30 constitute prime mover control means.

The control circuit 30 constitutes a determination means, a timing means, and a calculation means, and is connected to a microcomputer, etc., and includes an engine speed setting device (which detects the operation amount of the fuel lever in the driver's seat and outputs an operation amount signal corresponding to the operation amount signal). set rotation speed command means) 34, a selection switch 35 for selecting low-speed operation control, the above-mentioned potentiometer 25, and a pulse motor 23.
are connected. When low speed operation control is selected, a motor drive signal is supplied to the pulse motor 23 to lower the engine speed when predetermined conditions are met, as will be described later. Furthermore, if low-speed operation control is not selected, or if the condition is not satisfied even if it is selected, the control circuit 30 controls the governor lever position target value (engine target rotation The rotation direction and rotation amount of the pulse motor 23 are calculated based on the governor lever position detection value inputted from the potentiometer 25 (this is the engine rotation speed control value by the pulse motor 23, and is different from the actual engine rotation speed). Then, a motor drive signal is generated by a motor drive section (not shown) and supplied to the pulse motor 23.

Next, engine rotation speed control according to this embodiment will be explained with reference to the processing procedure shown in FIG.

In step S1, it is determined based on the selection signal from the selection switch 35 whether or not low-speed operation control is to be performed. If the answer is negative, the process advances to step S8, where a command is sent to the pulse motor 23 to operate at the set engine speed No. As described above, this set engine rotation speed command is obtained by calculating the deviation between the target rotation speed sent from the engine rotation speed setting device 34 and the engine rotation speed control value by the pulse motor 23 sent from the potentiometer 25 in the control circuit 30. Output. If low-speed driving control is selected, step SL is affirmed and the process proceeds to step S2, in which all operating members, ie, the travel pedal 6a, are activated.

It is determined whether the work operating levers 13a, 17a are in a neutral state. This is done based on signals from pressure switch 31 and limit switches 32,33. Step S
If 2 is affirmative, a timer (not shown) is activated to start measuring the delay time, and then the process proceeds to step S3, where it is determined whether or not a low-speed operation command is currently being issued. If step S3 is negative, the process proceeds to step S4, where a delay time TO corresponding to the set engine speed NO is calculated, and the process proceeds to step S5. This delay time To is made longer as the set engine rotation speed No becomes higher. On the other hand, if step S2 is negative, the timer is cleared in step S7 and the process proceeds to step S8.

In step S5, the elapsed time T after the timer activation is compared with the delay time To calculated in step S4, and T<To is determined.
If so, proceed to step S8 and set the set engine speed No.
Send a command to the pulse motor 23 to operate at T≧
If it is To, the process advances to step S6. In step S6,
A low speed operation command is sent to the pulse motor 23. That is, a command is sent to the pulse motor 23 to lower the engine rotation speed, which is being operated at the set engine rotation speed No, to the low speed rotation speed N1. This low-speed operation command is calculated by the control circuit 30 from the deviation between the preset low-speed rotation speed and the engine rotation speed control value detected by the potentiometer 25, and is output.

That is, in the embodiment described above, the rotation speed setting device 34
When the rotation speed of the engine 21 is set to the set rotation speed No., the travel pedals 6a, 13a are activated.

17a is operated, the engine 21 is at its set rotation speed N.

It is driven by In addition, the travel pedal 6a, the operation lever 13
When all of a and 17a become neutral and the delay time To has elapsed, the engine 21 is operated at a low rotation speed N1 lower than the set rotation speed No. This delay time To corresponds to the set rotational speed No, and is calculated so that it becomes longer as the set rotational speed N'O is higher.

Therefore, when the set rotation speed No. is high, the delay time T
O becomes long and, for example, if all operating members happen to be in a neutral state for a short period of time during work, low-speed operation control will not be performed. That is, the frequency of rotational speed fluctuations such as from set rotational speed to low speed rotational speed to set rotational speed is reduced, and the frequency of occurrence of black smoke and harsh sounds is reduced. Additionally, the flywheel accelerates less frequently, improving fuel efficiency. On the other hand, when the set rotational speed NO is low, the delay time To becomes short and low-speed operation control is performed frequently, resulting in improved fuel efficiency and reduced noise.

In addition, although the above-described embodiments have described a wheeled hydraulic excavator equipped with a hydraulic traveling circuit, the present invention can also be applied to a covered type hydraulic excavator without a traveling pedal and other construction machines. Furthermore, the present invention can also be applied to vehicles that are mechanically driven other than hydraulically driven, that is, vehicles that mechanically transmit engine power to the wheels. Furthermore, the engine speed can be set by operating the fuel lever to the desired position, but it is also possible to set the engine speed by using a digital setting method or by providing a button to increase or decrease the engine speed. good. Furthermore, although a method in which the governor is driven by a pulse motor has been shown, the present invention is not limited to this, and a method in which the fuel lever and the governor are mechanically linked and connected is not particularly limited. Further, although the control valve as the valve means is of a hydraulic pilot type, it may be of an electric type such as a proportional electromagnetic type. Further, the method for detecting whether or not the operating member is in the neutral position is not limited to the embodiment, and the number and arrangement of hydraulic motors and hydraulic cylinders as hydraulic actuators are also not limited to the embodiment.

G0 Effects of the Invention According to the present invention, when controlling the low-speed operation of the prime mover, a delay time corresponding to the set rotation speed is calculated, and when this delay time has elapsed after all operating members are in the neutral state, the prime mover starts rotating. Since the number of rotations is lowered, low-speed operation is performed less frequently when the set rotation speed is high, which reduces the generation of black smoke, reduces harsh noise, and reduces flywheel acceleration, resulting in improved fuel efficiency. will improve. Furthermore, when the set rotational speed is low, low-speed operation is performed more frequently, which also improves fuel efficiency.

[Brief explanation of the drawing]

FIG. 1 is a complaint correspondence diagram. 2 and 3 show an embodiment in which the present invention is applied to a wheeled hydraulic excavator. FIG. 2 is an overall configuration diagram thereof, and FIG. 3 is a flowchart showing an example of its processing procedure. 1: Hydraulic pump 2.11.15: Hydraulic pilot type control valve 4: Hydraulic motor 6: Pilot valve 6a: Travel pedal 12.16: Working actuator 13.17: Pilot valve 13a, 17a: Operation lever 14: Hydraulic pump 21: Engine 21a: Governor 23: Pulse motor 25: Potentiometer 30: Control circuit 31: Pressure switch 32: Limit switch 34: Engine speed setting device 35: Selection switch 100: Prime mover 101: Hydraulic pump 102: Hydraulic actuator 103: Valve Means 104: Operation member 105: Set rotation speed command means 106 2. Rotation speed control means 107: Detection means 108 2. Judgment means 109: Timing means 110: Calculation means

Claims (1)

[Scope of Claims] A hydraulic pump driven by a prime mover; at least one hydraulic actuator driven by pressure oil discharged from the hydraulic pump; valve means for controlling the operation of the hydraulic actuator; and the hydraulic actuator. an operating means for controlling the operation of the hydraulic actuator by operating the valve means; a set rotation speed command means for arbitrarily commanding a set rotation speed of the prime mover; A prime mover rotation speed control device for a hydraulic construction machine, comprising a prime mover control means for controlling the prime mover so that the operating means is in a neutral position; a determining means for determining whether at least one of the operating means is in the operating position or all of the operating means are in the neutral position, based on a detection result; and a determining means for determining that all of the operating means are in the neutral position. and a calculation means that calculates a delay time corresponding to the set rotation speed commanded by the set rotation speed command means, such that the higher the set rotation speed is, the longer the delay time is. The prime mover control means operates the prime mover at the set rotational speed when the determining means determines that at least one of the operating members is in the operating position, and the determining means determines that all of the operating members are in the neutral position. When it is determined that the condition is the same, the timing means controls the prime mover so that the prime mover is operated at a low rotational speed lower than the set rotational speed when the timer measures the delay time calculated by the calculation means after the determination. A prime mover rotation speed control device for hydraulic construction machinery, characterized by: