JP2009264211A - Prime mover rotational speed control device of construction machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suitably control an engine speed while preventing excessive rotation of a traveling motor. <P>SOLUTION: The prime mover rotational speed control device of the construction machine includes hydraulic pumps 11 and 12 driven by an engine 10, traveling motors 5a and 5b rotated by pressure oil from the hydraulic pumps 11 and 12, a hydraulic actuator for working driven by the pressure oil from the hydraulic pumps 11 and 12, control valves 13 and 14 for controlling flow of the pressure oil from the hydraulic pumps 11 and 12 to the traveling motors 5a and 5b, control valves 17 and 18 for controlling flow of the pressure oil from the hydraulic pumps 11 and 12 to the hydraulic actuator for working, operation members 15 and 16 for operating the control valves 13 and 14, and operation members 17a and 18a for controlling the control valves 17 and 18, and determines whether the state is the traveling single operation state or not by a signal from a traveling detector 22 and a work detector 23. During traveling single operation, larger the traveling operation amount is, more largely the engine speed is reduced. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a motor speed control device for a construction machine such as a hydraulic excavator.

  In this type of construction machine, in recent years, there is a tendency to reduce the travel motor in terms of efficiency and cost. However, if the travel motor is reduced in size, an increase in the speed of the travel motor becomes a problem. Conventionally, there has been known an apparatus in which the upper limit of the engine speed is set lower in single operation only for traveling than in combined operation of traveling and work to prevent over-rotation of the traveling motor (for example, patents). Reference 1).

JP 2002-130003 A

  However, since the apparatus described in Patent Document 1 uniformly restricts the upper limit of the engine speed to a predetermined speed during a single traveling operation, the engine speed cannot be optimally controlled.

A prime mover rotation speed control device for a construction machine according to the present invention includes a hydraulic pump driven by an engine, a traveling hydraulic motor rotating by pressure oil from the hydraulic pump, and a working hydraulic actuator driven by pressure oil from the hydraulic pump. A travel control valve that controls the flow of pressure oil from the hydraulic pump to the travel hydraulic motor, a work control valve that controls the flow of pressure oil from the hydraulic pump to the work hydraulic actuator, and a travel control valve It is determined whether or not the traveling operation member for operating the operation control member for operating the work control valve, the traveling operation member is operated, and the traveling operation member is not operated and the traveling operation member is not operated. First detecting means for detecting, detecting means for detecting a physical quantity having a correlation with the rotational energy of the traveling hydraulic motor, rotational speed setting means for setting a target rotational speed of the engine, If it is determined that the traveling alone operation state by determining means, characterized in that it comprises a rotational speed control means for reducing the engine rotational speed than the target rotational speed according to a physical quantity detected by the detecting means.
The detection means is configured as an operation amount detection means for detecting an operation amount of the travel operation member. When the detected operation amount of the travel operation member is larger than a predetermined value, the engine speed is more than when it is less than the predetermined value. It can also be greatly reduced.
The detection means is configured as a discharge pressure detection means for detecting the discharge pressure of the hydraulic pump, and when the detected discharge pressure of the hydraulic pump is larger than a predetermined value, the engine speed is greatly reduced than when it is lower than the predetermined value. You can also.
The travel hydraulic motor is a variable motor whose capacity can be changed, and the detection means is configured as a capacity detection means for detecting the capacity of the travel hydraulic motor, and the detected capacity of the travel hydraulic motor is larger than a predetermined value. And engine speed can also be reduced significantly rather than the time below a predetermined value.

  According to the present invention, since the engine speed is reduced according to the predetermined physical quantity during the single traveling operation, the engine speed can be optimally controlled.

-First embodiment-
A first embodiment of a prime mover rotation speed control device for a construction machine according to the present invention will be described below with reference to FIGS.
FIG. 1 is a perspective view of a hydraulic excavator that is an example of a construction machine to which the prime mover rotation speed control device according to the first embodiment is applied. This hydraulic excavator includes a traveling body 1, a revolving body 2 that is turnably mounted on the traveling body, and a work device 3 that includes a boom BM, an arm AM, and a bucket BC that are rotatably provided on the revolving body 2. Have

  The boom BM is driven by the boom cylinder 3a, the arm AM is driven by the arm cylinder 3b, and the bucket BC is driven by the bucket cylinder 3c. A crawler belt 4 is attached to each of the left and right sides of the traveling body 1. Each crawler belt 4 is driven by a traveling hydraulic motor 5, and a hydraulic excavator travels. The left and right traveling hydraulic motors 5 may be represented by 5a and 5b, respectively.

  FIG. 2 is a diagram mainly showing a traveling hydraulic circuit of the hydraulic excavator in FIG. 1. A pair of variable displacement hydraulic pumps 11, 12 are connected to the output shaft of the engine 10, and these hydraulic pumps 11, 12 are driven by the engine 10. The pressure oil from the hydraulic pumps 11 and 12 is supplied to the left and right hydraulic motors 5a and 5b via the direction control valves 13 and 14, respectively. The tilt angles of the hydraulic pumps 11 and 12 are controlled by driving the regulators 11a and 12a, respectively.

  Pilot pressures a to d corresponding to the operation amounts of the travel operation members 15 and 16 act on the direction control valves 13 and 14, respectively, and the direction control valves 13 and 14 are switched by the pilot pressures a to d. When the operation members 15 and 16 are not operated, the directional control valves 13 and 14 are switched to the neutral position, and supply of pressure oil to the hydraulic motors 5a and 5b is blocked. When the operation members 15 and 16 are operated, pressure oil is supplied to the hydraulic motors 5a and 5b by switching the direction control valves 13 and 14, and the hydraulic motors 5a and 5b rotate.

  Pressure oil from the hydraulic pumps 11 and 12 is also supplied to other working hydraulic actuators via the direction control valves 17 and 18. For example, the pressure oil from the hydraulic pump 11 is supplied to the boom cylinder 3a, the arm cylinder 3b, and the bucket cylinder 3c, and the pressure oil from the hydraulic pump 12 is supplied to the boom cylinder 3a, the arm cylinder 3b, and the turning hydraulic motor. In practice, more working direction control valves are provided, but the illustration is omitted. The direction control valves 17 and 18 are operated by operation members 17a and 18a, respectively.

  The controller 20 includes an arithmetic processing unit having a CPU, ROM, RAM, and other peripheral circuits. The controller 20 includes a rotation speed setting dial (EC dial) 21 for setting the engine rotation speed by a passenger's dial operation, a travel detector 22 for detecting the presence or absence of a travel operation, and a work detector for detecting the presence or absence of a work operation. 23 and a pressure sensor 24 are connected.

  The pressure sensor 24 is provided in a pilot pressure supply circuit to the direction control valves 13 and 14, and the operation amount of the operation members 15 and 16 is detected by the pressure sensor 24. The travel detector 22 is a pressure switch that is turned on when, for example, the travel pilot pressure is applied to the direction control valves 13 and 14, and the work detector 23 is the work pilot pressure that is applied to the direction control valves 17 and 18. Sometimes it is a pressure switch that turns on.

  The controller 20 controls the engine speed by outputting a control signal to the engine speed control unit 25 by a process described later. The engine speed control unit 25 includes a motor that drives a governor lever. Instead of mechanically driving the governor lever, the engine speed control unit 25 can be configured by a so-called electronic governor.

  FIG. 3 is a block diagram showing the configuration of the prime mover rotational speed control apparatus according to the first embodiment. In the rotational speed setting circuit 201, a target rotational speed N corresponding to the operation amount S of the EC dial 21 is set based on a predetermined characteristic f1 shown in the figure. According to the characteristic f1, as the manipulated variable S increases, the target rotational speed N gradually increases from the minimum rotational speed N0 (idle rotational speed) to the maximum rotational speed N1.

  The coefficient setting circuit 202 sets a coefficient α1 corresponding to the target rotational speed N based on a predetermined characteristic f2 shown in the figure. According to the characteristic f2, the coefficient α1 is 0 when the target rotational speed N is equal to or smaller than the predetermined value N2, the coefficient α1 is 1 when the target rotational speed N is equal to or larger than the predetermined value N3, and the target rotational speed N is in the range from N2 to N3. As the target rotational speed N increases, the coefficient α1 increases linearly from 0 to 1. The predetermined value N2 is equal to N0, for example, and the predetermined value N3 is equal to N1, for example. N2 may be set larger than N0 and N3 may be set smaller than N1.

  The rotation speed setting circuit 203 sets a deceleration rotation speed ΔN corresponding to the detection value P of the pressure sensor 24 based on a predetermined characteristic f3 shown in the figure. According to the characteristic f3, when the detected value P is equal to or smaller than the predetermined value P1, the deceleration rotational speed ΔN is 0, and when the detected value P is equal to or larger than the predetermined value P2, the rotational speed ΔN is the predetermined value ΔN1, and the detected value P is from P1 to P2. Within the range, as the detection value P increases, the deceleration rotational speed ΔN increases linearly from 0 to ΔN1. For example, when the detected value is P3, the deceleration rotational speed is ΔN1 / 2. The predetermined value ΔN1 is set equal to the difference (N3−N2) between N2 and N3 of the coefficient setting circuit 202. The predetermined value P1 corresponds to the minimum operation of the operation members 15 and 16, the predetermined value P2 corresponds to the maximum operation, and the predetermined value P3 corresponds to the half operation.

  The determination circuit 204 determines whether or not the traveling operation members 15 and 16 are operated by the signals from the traveling detector 22 and the work detector 23 and the working operation members 17a and 18a are not operated, that is, traveling. It is determined whether or not it is in a single operation state. When it is determined that the vehicle is operating alone, the determination circuit 204 turns on the timer, and the coefficient setting circuit 205 sets the coefficient α2. In this case, the coefficient setting circuit 205 gradually increases the coefficient α2 from 0 to 1 as time elapses after the timer is turned on.

  A signal from the determination circuit 204 is also output to the switching circuit 206 and the switch circuit 210. When it is determined that the vehicle is operating alone, the switching circuit 206 switches the terminal to the contact a side, and the switch circuit 210 closes the terminal. When it is determined that the operation is other than the traveling single operation, the switching circuit 206 switches the terminal to the contact b side, and the switch circuit 210 opens the terminal.

  The multiplication circuit 208 multiplies the deceleration rotation speed ΔN set by the rotation speed setting circuit 203 by a coefficient α2. In the setting circuit 207, the coefficient α2 = 1 is set in advance, and when the switching circuit 206 is switched to the contact b side, the multiplication circuit 208 multiplies ΔN by 1. When the switching circuit 206 is switched to the contact a side, ΔN is multiplied by the coefficient α2 set by the coefficient setting circuit 205. The multiplication circuit 209 multiplies the value obtained by multiplying the deceleration rotational speed ΔN by the coefficient α2 and the coefficient α1 set by the coefficient setting circuit 202 to calculate the deceleration rotational speed ΔN ′ (= ΔN × α2 × α1).

  The subtraction circuit 211 subtracts the deceleration rotation speed ΔN ′ from the target rotation speed N set by the rotation speed setting circuit 201 in accordance with the opening / closing of the switch circuit 210. In this case, if the switch circuit 210 is closed, a value (N−ΔN ′) obtained by subtracting ΔN ′ from the target rotational speed N is output as the final target rotational speed N. If the switch circuit 210 is open, the target rotational speed N set by the rotational speed setting circuit 201 is output as it is as the final target rotational speed N. The engine speed control unit 25 controls (feedback control) the engine speed so that the actual speed of the engine 10 becomes equal to the final target speed N.

The main operation of the prime mover control device according to the first embodiment will be described with reference to the time chart of FIG.
First, in a state where the rotation speed setting dial 21 is set to the maximum rotation speed N1, the traveling operation members 15 and 16 are operated to the maximum, and the operation operation members 17a and 18a are also operated together (combined operation). Is assumed. At this time, the detection value of the pressure sensor 24 is P2. During the composite operation, the switch circuit 210 is opened, and the engine speed is controlled to the maximum speed N1 set by the speed setting circuit 201 (time t0).

  When the operation of the work operation members 17a and 18a is stopped at time t1 from this state, the operation becomes a traveling single operation, the timer is turned on, and the switch circuit 210 is closed. At this time, the coefficient α2 set by the coefficient setting circuit 205 gradually increases with time. For this reason, the deceleration rotational speed ΔN ′ gradually increases, the engine rotational speed gradually decreases, and finally the engine rotational speed decreases by the predetermined rotational speed ΔN1 set by the rotational speed setting circuit 203 (time point). t2). As a result, the pump discharge amount is suppressed, and overrunning of the traveling motors 5a and 5b can be prevented.

  Thereafter, at time t3, the operation operation members 17a and 18a are operated, and when the traveling single operation is finished, the switch circuit 210 is opened. As a result, the engine speed is increased by a predetermined speed ΔN1, and the engine speed is controlled to the set speed set by the speed setting circuit 201. In this case, the timer may be turned on at the end of the traveling single operation similarly to the start of the traveling single operation, and the engine speed may be gradually increased as indicated by the dotted line.

  On the other hand, when the traveling operation members 15 and 16 are half-operated during the traveling single operation, the detected value of the pressure sensor 24 becomes P3 (<P2). In this case, the engine speed gradually decreases with time as indicated by the dotted line in the figure at time t1, and finally decreases by ΔN1 / 2. As a result, when the travel operation amount is small, the decrease amount of the engine speed is suppressed, and a travel feeling that matches the travel operation is obtained. In this case, since the switching amount of the directional control valves 13 and 14 is small during the half operation, the amount of pressure oil supplied to the traveling motors 5a and 5b does not become excessive even if the amount of decrease in the engine speed is reduced, and the traveling motor 5a. , 5b does not over-rotate.

  When the set rotational speed by the rotational speed setting dial 21 is decreased, the coefficient α1 set by the coefficient setting circuit 202 is decreased. As a result, when the set rotational speed N is small, the deceleration rotational speed ΔN ′ decreases, so that the difference between the actual engine rotational speed and the set rotational speed N is small, and the traveling feeling at the time of traveling independent operation is improved. In this case, since the set rotational speed N is small, the amount of pressure oil supplied to the traveling motors 5a and 5b does not become excessive even if the amount of decrease in the engine rotational speed is reduced, and the traveling motors 5a and 5b may overrotate. Absent.

According to 1st Embodiment, there can exist the following effects.
(1) Since the engine speed is reduced in accordance with the amount of operation of the travel operation members 15 and 16 during single travel operation, the pump discharge amount is suppressed and the travel motors 5a and 5b are downsized. Even so, overrunning of the traveling motors 5 and 5b can be prevented. In this case, the larger the operation amount of the travel operation members 15 and 16 is, the larger the deceleration rotational speed ΔN ′ of the engine 10 is. Therefore, the reduction amount of the engine rotational speed is not excessively increased, and the engine rotational speed is optimally controlled. be able to.
(2) Since the engine speed is gradually decreased with the passage of time during the traveling single operation, the shock at the start of the traveling single operation can be reduced.
(3) When the set speed of the speed setting dial 21 is small, the decelerating speed ΔN ′ of the engine 10 is made small. Therefore, in the low speed range where the overspeed of the travel motors 5a and 5b does not matter, the operator's intention It can run under the engine speed. Further, it is possible to prevent the engine speed from becoming smaller than the minimum speed N0.

-Second Embodiment-
With reference to FIG. 5, a second embodiment of a prime mover rotation speed control device for a construction machine according to the present invention will be described.
In the first embodiment, the reduction amount of the engine speed is changed in accordance with the operation amount of the travel operation members 15 and 16, but in the second embodiment, the travel motors 5a and 5b are variable. It is configured as a capacity type hydraulic motor, and the amount of decrease in engine speed is changed according to the motor tilt. In the following description, differences from the first embodiment will be mainly described.

  The travel motors 5a and 5b are two-speed variable motors that can change the tilt between a small tilt and a large tilt, and the driving pressure of the travel motors 5a and 5b is fed back to the motor regulator to change the motor tilt. The That is, the motor tilt qm is large when the motor drive pressure is greater than the predetermined value Pa, and the motor tilt qm is small when the motor drive pressure is equal to or less than the predetermined value Pa.

  FIG. 5 is a block diagram showing the configuration of the prime mover rotational speed control apparatus according to the second embodiment. In addition, the same code | symbol is attached | subjected to the location same as FIG. The motor tilt qm is detected by the tilt angle detector 220, and a signal from the tilt angle detector 220 is input to the rotation speed setting circuit 221. The rotation speed setting circuit 221 sets a deceleration rotation speed ΔN corresponding to the motor tilt qm based on a predetermined characteristic f4 shown in the figure. According to the characteristic f4, when the motor tilt qm is small, the deceleration rotational speed ΔN is ΔN1, the deceleration rotational speed decreases as the motor tilt qm increases, and when the motor tilt qm is large, the rotational speed decreases. The number ΔN becomes zero.

  In the second embodiment, during the traveling single operation, the deceleration rotational speed ΔN ′ is large when the motor tilt qm is small, and the deceleration rotational speed ΔN ′ is small when the motor tilt qm is large. As a result, the amount of decrease in the engine speed does not become too large, and the engine speed can be optimally controlled in accordance with the travel situation while preventing the travel motors 5a and 5b from over-rotating.

  In the above-described embodiment, the reduction amount of the engine speed is changed according to the operation amount of the traveling operation members 15 and 16 or the motor tilt angle qm, but the traveling operation members 15 and 16 and the motor The reduction amount of the engine speed may be changed in consideration of both the tilt angle qm. An example is shown in FIG.

  In FIG. 6, a coefficient setting circuit 222 sets a coefficient α3 corresponding to the motor tilt qm based on a predetermined characteristic f5 shown in the figure. According to the characteristic f5, the coefficient α3 is 1 when the motor tilt is small, the coefficient α3 decreases as the motor tilt increases, and the coefficient α3 becomes 0.5 when the motor tilt is large. . The multiplication circuit 223 multiplies the deceleration speed ΔN set by the speed setting circuit 203 by a coefficient α3. As a result, the greater the travel operation amount and the smaller the motor tilt qm, the greater the decelerating speed ΔN ′, and it is possible to reliably prevent the travel motors 5a and 5b from over-rotating.

  The rotation of the traveling motors 5a and 5b is also affected by the discharge pressure of the hydraulic pumps 11 and 12 acting on the motors 5a and 5b. Therefore, the pump discharge pressure Pp may be detected by a pressure sensor, and the deceleration rotational speed ΔN ′ may be changed according to the pump discharge pressure Pp. An example is shown in FIG.

  In FIG. 7, the pump discharge pressure Pp is detected by the pressure sensor 24. The rotation speed setting circuit 225 calculates a decelerating rotation speed ΔN corresponding to the pump discharge pressure Pp according to a predetermined characteristic f6 shown in the figure. According to the characteristic f6, when the pump discharge pressure Pp is equal to or less than the predetermined value Pp1, the deceleration rotational speed ΔN is 0, and when the pump discharge pressure Pp is equal to or greater than the predetermined value Pp2, the deceleration rotational speed ΔN is the predetermined value ΔN1 and the pump discharge pressure Pp is Pp1. In the range from to Pp2, the deceleration rotational speed ΔN increases linearly from 0 to ΔN1 as the pump discharge pressure Pp increases. As a result, as the pump discharge pressure pp increases, the amount of decrease in engine speed increases, and the engine speed can be optimally controlled.

  In the above-described embodiment, the engine speed is reduced from the set speed N according to the travel operation amount, the motor tilt qm, and the pump discharge pressure Pp during the single travel operation, but only during the single travel operation. Alternatively, the engine speed may be reduced below the set speed N even when the vehicle is not running and not working. In this case, it is determined based on signals from the travel detector 22 and the work detector 23 whether or not the vehicle is in a non-running and non-working non-operating state. What is necessary is just to control to Na. Thereby, fuel consumption and noise can be reduced.

  In this case, it is preferable that the reduction amount (N-Na) of the engine speed is equal to or larger than ΔN1 described above. As a result, the engine speed is higher at the time of traveling single operation than at the time of non-operation, so that the engine speed can be quickly returned to the set speed N at the start of work by the combined operation (time t3 in FIG. 4). Work efficiency is improved. Note that the non-operation state may be determined by other than the determination circuit 204, and the configuration of the second determination unit is not limited to that described above.

  In the above embodiment, the travel detector 22 and the work detector 23 detect the operation of the travel operation members 15 and 16 and the operation of the work operation members 17a and 18a, respectively, and determine the travel single operation state. The configuration of the determination circuit 204 as one determination unit is not limited to this. The operation members 15 and 16 operate the direction control valves 13 and 14 as travel control valves, and the operation members 17a and 18a operate the direction control valves 17 and 18 as work control valves. The members 15, 16, 17a, 18a can be constituted by levers or pedals.

  Although the target rotational speed N of the engine 10 is set by the rotational speed setting dial 21, the rotational speed setting means is not limited to this. For example, the target rotational speed N can be set in advance in the controller 20 as a fixed value instead of being made variable by manual operation. The pressure sensor 24, the tilt angle detector 220, and the pressure sensor 224 as detection means detect the travel operation amount, the motor tilt qm, and the pump discharge pressure Pp, respectively, and the engine speed is determined according to these detected values. However, other physical quantities having a correlation with the rotational energy (motor rotational speed and motor pressure) of the traveling motors 5a and 5b may be detected by other detection means. If the engine speed is reduced below the target speed N according to a physical quantity having a correlation with the rotational energy at the time of traveling alone operation, the configuration of the controller 20 and the speed control unit 25 as the speed control means is as follows. It is not restricted to what was mentioned above. Although the engine speed is gradually reduced at the start of the traveling single operation, the engine speed reduction pattern is not limited to this.

  In the above embodiment, the operation amount of the operation members 15 and 16 is detected by the pressure sensor 24 (FIG. 3). However, the operation amount may be directly detected by providing a potentiometer or the like in the operation portion of the operation members 15 and 16. The operation amount detection means is not limited to that described above. In the above embodiment, the pump discharge pressure Pp is detected by the pressure sensor 224 (FIG. 7), and the motor tilt qm is detected by the tilt angle detector 220 (FIG. 5). However, the discharge pressure detection means and the capacity detection means The configuration is not limited to this.

  Although the deceleration rotational speed ΔN is increased as the travel operation amount increases, at least when the travel operation amount is greater than a predetermined value (for example, an operation corresponding to the predetermined pilot pressure P2 in FIG. 3), the engine speed is lower than when the travel operation amount is less than the predetermined value. If the number is greatly reduced, the configuration of the controller 20 is not limited to that shown in FIG. As the motor tilt qm increases, the deceleration rotational speed ΔN is increased. However, at least when the motor capacity is larger than a predetermined value (for example, a small tilt in FIG. 5), the engine rotational speed is greatly reduced compared to when the motor rotational speed is less than the predetermined value. In this case, the configuration of the controller 20 is not limited to that shown in FIG. As the pump discharge pressure Pp is increased, the deceleration rotational speed ΔN is increased. However, at least when the pump discharge pressure is greater than a predetermined value (for example, Pp1 in FIG. 7), the engine speed is greatly reduced compared to when the pump discharge pressure Pp is lower than the predetermined value. If so, the configuration of the controller 20 is not limited to that shown in FIG.

  The example in which the prime mover rotational speed control device according to the present embodiment is applied to a hydraulic excavator has been described above, but the present invention can be similarly applied to other construction machines having traveling motors 5a and 5b such as a crawler crane. That is, the present invention is applicable to construction machines having working hydraulic actuators other than the boom cylinder 3a, the arm cylinder 3b, and the bucket cylinder 3c, and the present invention is not limited to the embodiment as long as the features and functions of the present invention can be realized. It is not limited to the prime mover rotation speed control device for construction machinery.

1 is a perspective view of a hydraulic excavator to which a prime mover rotation speed control device according to an embodiment of the present invention is applied. 1 is a hydraulic circuit diagram showing a schematic configuration of a prime mover rotational speed control device according to a first embodiment. The block diagram which shows the principal part structure of the motor | power_engine rotational speed control apparatus which concerns on 1st Embodiment. The figure which shows an example of operation | movement of the motor | power_engine rotation speed control apparatus which concerns on 1st Embodiment. The block diagram which shows the principal part structure of the motor | power_engine rotational speed control apparatus which concerns on 2nd Embodiment. The figure which shows the modification of FIG. The block diagram which shows the other structure of the motor | power_engine rotational speed control apparatus which concerns on embodiment of this invention.

Explanation of symbols

11, 12 Hydraulic pumps 5a, 5b Hydraulic motor 3a Boom cylinder 3b Arm cylinder 3c Bucket cylinders 13, 14, 17, 18 Directional control valves 15, 16 Traveling operation members 17a, 18a Work operation members 20 Controller 21 Speed setting dial 22 Traveling detector 23 Work detector 24 Pressure sensor 25 Rotational speed control unit 220 Tilt angle detector 224 Pressure sensor

Claims (5)

A hydraulic pump driven by an engine;
A traveling hydraulic motor that is rotated by pressure oil from the hydraulic pump;
A working hydraulic actuator driven by pressure oil from the hydraulic pump;
A travel control valve that controls the flow of pressure oil from the hydraulic pump to the travel hydraulic motor;
A work control valve for controlling the flow of pressure oil from the hydraulic pump to the work hydraulic actuator;
A travel operation member for operating the travel control valve;
An operation member for operating the operation control valve;
First determination means for determining whether or not the traveling operation member is operated and the working operation member is not operated;
Detecting means for detecting a physical quantity having a correlation with rotational energy of the traveling hydraulic motor;
A rotational speed setting means for setting a target rotational speed of the engine;
And a rotation speed control means for reducing the engine rotation speed from the target rotation speed in accordance with the physical quantity detected by the detection means when the first determination means determines that the vehicle is operating alone. A prime mover speed control device for construction machinery. In the prime mover rotation speed control device for the construction machine according to claim 1,
The detection means is an operation amount detection means for detecting an operation amount of the travel operation member,
When the detected operation amount of the traveling operation member is greater than a predetermined value, the rotation speed control means significantly reduces the engine rotation speed than when it is less than or equal to a predetermined value. Control device. In the prime mover rotation speed control device for the construction machine according to claim 1,
The detecting means is a discharge pressure detecting means for detecting a discharge pressure of the hydraulic pump;
When the detected discharge pressure of the hydraulic pump is larger than a predetermined value, the rotational speed control means greatly reduces the engine rotational speed than when it is lower than the predetermined value. . In the prime mover rotation speed control device for the construction machine according to claim 1,
The traveling hydraulic motor is a variable motor whose capacity can be changed,
The detection means is a capacity detection means for detecting the capacity of the traveling hydraulic motor,
The engine speed control for the construction machine is characterized in that the engine speed is greatly reduced when the detected capacity of the traveling hydraulic motor is larger than a predetermined value, when the detected capacity is larger than a predetermined value. apparatus. In the motor | power_engine rotation speed control apparatus of the construction machine of any one of Claims 1-4,
A second determination means for determining whether or not the travel operation member is non-operated and the work operation member is non-operated;
When the second determination means determines that the engine speed is in a non-operating state, the engine speed control unit reduces the engine speed more than when the engine is determined to be in the travel-only operation state. Rotational speed control device.

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