JP2008150877A - Hydraulic pump control device of construction equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydraulic pump control device of construction equipment, which can increase a pump input horsepower only as needed, and holds down the pump input horsepower if not necessary, to thereby reduce fuel consumption of an engine. <P>SOLUTION: The hydraulic pump control device of the construction equipment is provided with a controller 10 which regulates a discharge amount of a hydraulic pump 2 by a regulator 3, based on a discharge pressure of a variable delivery hydraulic pump 2 driven by the engine 1, and has a group of horsepower constant curves (H, S, L) for controlling pump input horsepower to a constant value in each different working mode. Herein the controller 10 is set such that if an operating lever 6a for operating an actuator is operated at a predetermined reference speed or below, the horsepower constant curve in the working mode applied at the time is changed to the lower horsepower constant curve in the working mode of the pump input horsepower, and that if the operating lever 6a is operated at a speed in excess of the predetermined reference speed, the horsepower constant curve in the working mode applied at the time is maintained. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a hydraulic pump control device for a construction machine such as a hydraulic excavator, and in particular, a hydraulic pump for a construction machine that performs work by switching to a plurality of work modes while controlling the discharge amount and discharge pressure of the hydraulic pump. The present invention relates to a control device.

  Conventionally, a construction machine such as a hydraulic excavator has been used in which an actuator is operated by switching to various work modes by changing the engine speed according to the working state and controlling the discharge pressure and discharge amount of the hydraulic pump. Known (see, for example, Patent Document 1 and Patent Document 2). In Patent Document 1 and Patent Document 2, the engine speed is changed according to the working state to realize the pump characteristics as shown in FIG.

  FIG. 3 is a pressure-flow rate curve diagram of the variable displacement hydraulic pump installed in the hydraulic excavator, where the horizontal axis indicates the hydraulic pump discharge pressure (P) and the vertical axis indicates the hydraulic pump discharge amount (Q). Curve “H” is a constant horsepower curve used in heavy excavation mode (hereinafter referred to as “H mode”) under heavy load, and curve “S” is standard excavation mode (hereinafter referred to as “S mode”) under standard load. The constant horsepower curve used in, curve "L" indicates a constant horsepower curve used in the finish excavation mode (hereinafter referred to as L mode).

  FIG. 4 shows the relationship between the engine speed (N) and the torque (T) in each mode. The curve “H” in FIG. 4 is required in the H mode. The engine speed, curve “S” indicates the engine speed required in the S mode, and curve “L” indicates the engine speed required in the L mode. As shown in FIG. 4, the engine speed increases each time the mode is changed from the L mode to the S mode and from the S mode to the H mode. Therefore, when the mode is switched from the H mode to the S mode, and from the S mode to the L mode, the engine speed also decreases, and theoretically, fuel consumption and noise are also reduced.

Conventionally, when working on a construction machine, the driver selects one of the above modes to perform the work according to the load of the work.
JP-A-2-104992 JP-A-11-125187

  However, in actual work, the number of engine revolutions, that is, the pump input horsepower, is most required when the actuator is activated and when the load is high. That is, after entering the actual work after starting the actuator, the work in each mode does not require a large pump input horsepower. In other words, there are many cases where it is sufficient to work in a work mode that is one step lower in which the engine speed can be lowered. The design was based on the input horsepower. For this reason, the pump input horsepower is large in each mode, and the engine speed is also high. For this reason, the amount of fuel consumption was large and wasteful.

  Therefore, there is a technical problem to be solved in order to increase the pump input horsepower only when necessary, and to reduce the fuel consumption of the engine by suppressing the pump input horsepower when it is unnecessary. The present invention aims to solve this problem.

  The present invention has been proposed to achieve the above object, and the invention according to claim 1 is characterized in that the discharge amount of the hydraulic pump is controlled by a regulator based on the discharge pressure of the variable displacement hydraulic pump driven by the engine. Operation of an operation lever for operating an actuator in a hydraulic pump control device of a construction machine having a flow rate control means having a constant horsepower curve group for adjusting and controlling the pump input horsepower to be constant for different work modes When the operation lever is operated at a predetermined speed or less when the operation lever is operated at a predetermined speed or less, a constant horsepower curve of the work mode used at that time is provided. If the operation lever is operated at a speed exceeding the predetermined speed, change to a constant horsepower curve for the work mode with a lower pump input horsepower. In to maintain a horsepower constant curve of work mode are used to provide a hydraulic pump control system for a construction machine which characterized in that by setting the flow control means.

  According to this configuration, when the operation lever is operated at a predetermined speed or less, the flow rate control means has a constant horsepower curve in the work mode with a lower pump input horsepower than the constant horsepower curve in the work mode currently used. When the operation lever is operated exceeding a predetermined speed, the constant horsepower curve of the work mode used at that time is held. Therefore, it is possible to raise the engine rotational speed only when necessary to increase the pump input horsepower, and to keep the engine rotational speed low when not necessary, thereby reducing the total horsepower consumption.

  According to a second aspect of the present invention, when the operation lever is operated at a predetermined speed or less to be changed to a constant horsepower curve in another work mode, and then the discharge pressure of the hydraulic pump returns to the predetermined pressure, 2. The hydraulic pump control device for a construction machine according to claim 1, wherein the flow rate control means is set so as to return to the constant horsepower curve in the work mode.

  According to this configuration, when the discharge pressure of the hydraulic pump returns to a predetermined pressure, the hydraulic pump can be finely controlled by returning to the constant horsepower curve in the work mode before the change.

  According to a third aspect of the present invention, the flow rate control is performed so that the return to the constant horsepower curve in the work mode before the change is performed after the discharge pressure of the hydraulic pump has returned to a predetermined pressure for a predetermined time. 3. The hydraulic pump control device for a construction machine according to claim 2, wherein means are set.

  According to this configuration, the return to the work mode before the change is not made by the instantaneous pressure change, but is performed after the pressure return state of the discharge pressure of the hydraulic pump continues for a certain period of time. A stable switching of the curve becomes possible.

  The invention according to claim 4 is characterized in that the constant horsepower curve includes a constant horsepower curve in heavy excavation mode, a constant horsepower curve in standard excavation mode, and a constant horsepower curve in finish excavation mode. , 2 or 3 A hydraulic pump control device for a construction machine is provided.

  According to this configuration, it can be applied in switching between the heavy excavation mode and the standard excavation mode and between the standard excavation mode and the finish excavation mode.

  According to the first aspect of the invention, the pump input horsepower can be increased only when necessary, and the pump input horsepower can be suppressed when not required to reduce the total consumed horsepower. Reduce energy consumption.

  Since the invention according to claim 2 enables fine control of the pump input horsepower, it is possible to further reduce the fuel consumption than the fuel consumption of the engine in the effect of the invention according to claim 1 and to save energy. Can be promoted.

  According to the invention described in claim 3, since the return to the work mode before the change is made after the discharge pressure of the hydraulic pump is not returned by an instantaneous change and the pressure return of the discharge pressure is continued for a certain period of time. In addition to the effects of the invention described in 2, the stable control is possible.

  Since the invention according to claim 4 can be applied in the switching between the heavy excavation mode and the standard excavation mode and between the standard excavation mode and the finish excavation mode, the invention according to claim 1, 2 or 3 can be applied. In addition to the effect, the effect can be exhibited in a construction machine having a heavy excavation mode, a standard excavation mode, and a finish excavation mode.

  The operating speed of the operating lever that operates the actuator to achieve the purpose of increasing the pump input horsepower only when necessary and reducing the pump input horsepower when it is not needed to reduce engine fuel consumption. When the operation lever is operated at a predetermined speed or lower than the constant horsepower curve of the work mode used at that time. When the operation lever is operated beyond a predetermined speed, the constant horsepower curve of the working mode used at that time is maintained so as to maintain the constant horsepower curve of the low pump input horsepower working mode. Realized by setting the flow control means.

  Hereinafter, an embodiment of a hydraulic pump control device for a construction machine according to the present invention will be described. FIG. 1 is a control circuit of a hydraulic excavator shown as an example of a construction machine to which the present invention is applied.

  In FIG. 1, a hydraulic pump 2 driven by an engine 1 is a variable displacement hydraulic pump capable of adjusting a discharge amount of hydraulic oil by changing an inclined plate 9 by a regulator 3. 4 is supplied. A group of directional control valves 5 for controlling an actuator (not shown) are connected downstream of the center oil passage 4. The direction switching valve 5 is remotely operated by the pilot pressure of the remote control valve 6 interlocked with the operation of the operation lever 6a.

  The regulator 3 is provided with two oil chambers 3 a and 3 b. The oil chamber 3 a is negatively fed back from the branch oil passage 7 connected to the center oil passage 4, and the output of the hydraulic pump 2. Negative feedback is performed so that the torque is constant. As a result, the horsepower constant control is performed so that the output torque does not exceed the engine torque even if the pump discharge pressure changes. The oil chamber 3b is subjected to the secondary pressure Pf of the electromagnetic proportional valve 8 serving as a discharge amount control means, and sets and changes each horsepower constant curve (H, S, L) in the pressure-flow curve shown in FIG. It is configured to be able to.

  The solenoid of the electromagnetic proportional valve 8 is connected to the output side of the controller 10. In addition, the controller 10 has a work mode (pump input horsepower) selection switch 11, a main pressure sensor 12 that detects the discharge pressure of the hydraulic pump 2, and a pilot pressure sensor 13 that detects the pilot pressure of the remote control valve 6. It is connected. The pilot pressure sensor 13 detects the pilot pressure of the remote control valve 6 via the shuttle valve 14, and serves as a speed of the operation lever 6a, that is, a signal corresponding to the operation status of the operation lever 6a to the controller 10 as an operation status detection means. Output.

  The controller 10 is a flow rate control unit mainly composed of a microcomputer. The controller 10 switches the operation of the hydraulic excavator between the H mode (heavy excavation mode), the S mode (standard excavation mode), and the L mode (finish excavation mode). A function for setting a discharge amount and a discharge pressure of the hydraulic pump 2 is provided, and these functions are executed in accordance with a program procedure incorporated in the controller 10 in advance.

  In addition, the controller 10 has a control function in a manual operation mode in which the driver directly operates the selection switch 11 to switch the work mode, and the operation environment on the controller 10 side from the operation state of the operation lever 6a operated by the driver. It has a control function in an energy saving operation mode that saves fuel consumption by estimating and automatically changing to a work mode (H, S, L) suitable for the work environment. Note that switching between the manual operation mode and the energy saving operation mode is instructed by the driver by operating a switch (not shown).

(manual operation)
First, manual operation will be described. In the manual operation, as shown in FIG. 1, when the position “H” of the selection switch 11 is selected, the H mode is set. When the position “S” is selected, the S mode is selected. When the position “L” is selected, the L mode is set. become. Further, a control command is issued from the controller 10 to the regulator 3, and the discharge pressure and flow rate of the hydraulic pump 2 corresponding to each mode are controlled via the regulator 3. The hydraulic pump 2 is the hydraulic pump shown in FIG. The pump input horsepower in each mode is constant using the relationship between the discharge pressure and the discharge amount, and the constant horsepower curve group (H, S, L) in the heavy excavation mode, standard excavation mode, and finish excavation mode. To be adjusted. That is, in the H mode, a constant horsepower curve indicated by “H” in FIG. 3, in the S mode, a constant horsepower curve indicated by “S” in FIG. 3, and in the L mode, a constant horsepower curve indicated by “L” in FIG. It is adjusted as follows.

(Energy saving operation)
Next, the energy saving operation will be described. FIG. 2 is a flowchart showing an example of the control procedure of the controller during the energy saving operation. In this embodiment, in the case of the energy saving operation, the operation is set to start by either the H mode pump input horsepower or the S mode pump input horsepower.

When the energy saving operation is selected, in the initial mode setting (step ST1), when the operation is performed with the pump input horsepower by the constant horsepower curve H in the H mode, the process proceeds to step ST2, and the controller 10 operates the operation lever. The operation speed σ _{1 of} 6 a is detected by a signal from the pilot pressure sensor 13.

When the operation speed σ ₁ of the operation lever 6 a is operated faster than a predetermined reference speed σ _{HS and} the slope of the pressure increase detected by the pilot pressure sensor 13 exceeds a predetermined value ( σ ₁ > σ _HS ) remains at the H-mode pump input horsepower, and continues to send an H-mode signal from the controller 10 to the regulator 3 (step ST3).

On the other hand, when the operation speed σ ₁ of the operation lever 6a is operated at a slow speed equal to or less than the reference speed σ _{HS and} the slope of the pressure increase detected by the pilot pressure sensor 13 is equal to or less than a predetermined value (σ ₁ ≦ σ _HS ), The pump input horsepower is changed to S mode (step ST4).

From step ST3 or step ST4, the process proceeds to step ST5. When a predetermined time t has elapsed from the processing in step ST3 or step ST4 (step ST5), the pump discharge pressure _PH1 of the hydraulic pump 2 is detected by a signal from the main pressure sensor 12 (step ST6).

When the pump discharge pressure P _H1 exceeds the reference pressure P _HS and the load of the hydraulic pump 2 is heavy (P _H1 > P _HS ), the pump input horsepower in the H mode is kept (step ST7). On the other hand, when the pump discharge pressure P _H1 is equal to or lower than the reference pressure P _{HS and} the load of the hydraulic pump 2 is light (P _H1 ≦ P _HS ), the pump input horsepower is changed to the S-mode horsepower constant curve S (step ST8). . In addition, from step ST7 and step ST8, it returns to step ST2, respectively, and repeats the same operation | movement.

When the energy-saving operation is selected, and the initial mode setting (step ST1) is selected to perform the work with the pump input horsepower by the constant horsepower curve S in the S mode, the process proceeds to step ST12, and the controller 10 moves the operation lever 6a. The operation speed σ ₁ is detected by a signal from the pilot pressure sensor 13.

When the operating speed σ ₁ of the operating lever 6 a is operated faster than a predetermined reference speed σ _{SS and} the slope of the pressure increase detected by the pilot pressure sensor 13 exceeds a predetermined value (σ ₁ > σ _SS ), the S-mode pump input horsepower remains unchanged, and the controller 10 continues to send an S-mode signal to the regulator 3 (step ST13).

On the other hand, when the operating speed σ ₁ of the operating lever 6a is operated at a slow speed equal to or lower than the reference speed σ _{SS and} the slope of the pressure increase detected by the pilot pressure sensor 13 is equal to or lower than a predetermined value (σ ₁ ≦ σ _SS ), The pump input horsepower is changed to L mode (step ST14).

From step ST13 or step ST14, the process proceeds to step ST15. When a predetermined time t has elapsed from the processing in step ST13 or step ST14 (step ST15), the pump discharge pressure _PS1 of the hydraulic pump 2 is detected by a signal from the main pressure sensor 12 (step ST16).

When the pump discharge pressure P _S1 exceeds the reference pressure P _SS and the load of the hydraulic pump 2 is heavy (P _S1 > P _SS ), the pump input horsepower in the S mode remains as it is (step ST17). On the other hand, when the pump discharge pressure P _S1 is equal to or lower than the reference pressure P _{SS and} the load of the hydraulic pump 2 is light (P _S1 ≦ P _SS ), the pump input horsepower is changed to the horsepower constant curve L in the L mode (step ST18). . In addition, from step ST17 and step ST18, it returns to step ST2, respectively, and repeats the same operation | movement.

  As described above, in the control of the energy saving operation described above, only when necessary, the engine speed is increased to increase the pump input horsepower, and when it is unnecessary, the engine speed is decreased to reduce the pump input horsepower. Since the horsepower consumed in the engine can be reduced, the fuel consumption of the engine can be reduced.

  In the above embodiment, the operation state is grasped and the pilot pressure is directly detected by the pilot pressure sensor 13. However, for example, the operation state is grasped by detecting the fluctuation of the negative control pressure. Good.

  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 control circuit diagram of the hydraulic shovel applied to this invention. The flowchart which shows an example of the control procedure in this invention. The figure shows the pressure-flow characteristics of a general hydraulic pump, and shows a constant horsepower curve in heavy excavation mode, standard excavation mode, and finish excavation mode. The figure which shows the engine speed and torque relationship in a general hydraulic excavator.

Explanation of symbols

1 Engine 2 Variable displacement hydraulic pump 3 Regulator 4 Center oil path 5 Directional switching valve 6 Remote control valve 6a Operation lever 7 Branch oil path 8 Electromagnetic proportional valve (flow rate control means)
9 Inclined plate 10 Controller (Flow control means)
11 Selection switch 12 Main pressure sensor 13 Pilot pressure sensor (operation status detection means)
14 Shuttle valve

Claims (4)

A set of constant horsepower curves for adjusting the discharge amount of the hydraulic pump with a regulator based on the discharge pressure of a variable displacement hydraulic pump driven by the engine, and controlling the pump input horsepower to be constant for different work modes In a hydraulic pump control device for a construction machine provided with a flow rate control means having
An operation state detection unit that outputs a signal corresponding to an operation speed of an operation lever for operating the actuator to the flow rate control unit is provided. When the operation lever is operated at a predetermined speed or less, the operation lever is used at that time. When the operating lever is operated beyond a predetermined speed, the pump mode is changed to a constant horsepower curve for the pump input horsepower that is lower than the constant horsepower curve for the working mode. A hydraulic pump control device for a construction machine, wherein the flow rate control means is set so as to maintain a constant horsepower curve.   When the operation lever is operated at a predetermined speed or less to change to a constant horsepower curve for another work mode, and then the discharge pressure of the hydraulic pump returns to a predetermined pressure, the constant horsepower curve for the work mode before the change is changed. 2. The hydraulic pump control device for a construction machine according to claim 1, wherein the flow rate control means is set so as to return.   The return to the constant horsepower curve in the work mode before the change is made by setting the flow rate control means so that the state in which the discharge pressure of the hydraulic pump returns to a predetermined pressure is continued for a predetermined time. The hydraulic pump control device for a construction machine according to claim 2,   The construction machine according to claim 1, 2 or 3, wherein the constant horsepower curve has a constant horsepower curve in heavy excavation mode, a constant horsepower curve in standard excavation mode, and a constant horsepower curve in finish excavation mode. Hydraulic pump control device.

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