Patent Publication Number: US-11643793-B2

Title: Operation control device for working vehicle

Description:
TECHNICAL FIELD 
     The present invention relates to an operation control device for a working vehicle. 
     TECHNICAL BACKGROUND 
     Hydraulic shovels (excavators) are known as working vehicles. The hydraulic shovel is configured to comprise a traveling unit having right and left crawler mechanisms, a turning body pivotally provided on the top of the traveling unit, and a shovel device provided on the front of the turning body. As such a hydraulic shovel, there is known a hydraulic shovel which comprises a power supply unit having a battery and an inverter, an electric motor receiving electric power from the power supply unit to drive, a hydraulic pump driven by the electric motor, and a plurality of hydraulic actuators (hydraulic motors, hydraulic cylinders, etc.) receiving operating oil discharged from the hydraulic pump to operate and which is configured to make the crawler mechanisms, the shovel device, and the like operate by these hydraulic actuators so as to perform travelling, excavation, and the like. 
     As such hydraulic actuators, there are a travelling motor to make the crawler mechanisms operate, a turning motor to make the turning body pivot, a boom cylinder to make the shovel device operate, an arm cylinder, a bucket cylinder, a swing cylinder, a blade cylinder to make a blade vertically move, and so on. Among conventional hydraulic shovels, there is known a shovel which comprises an operation control device configured to drive a plurality of hydraulic pumps (including a pilot pump) by one electric motor and, using operating oil discharged from those hydraulic pumps, to make the above-mentioned plurality of hydraulic actuators operate and to generate pilot pressures. This operation control device needs to drive all the hydraulic pumps by one electric motor such that pump discharge pressure corresponds to the highest pressure under load among all the hydraulic actuators, and thus excess energy consumption by that electric motor is large in amount. 
     Accordingly, there is also known an operation control device which comprises two electric motors and is configured to make the travelling motor and the hydraulic cylinders (boom cylinder and the like) of the shovel device operate using operating oil from a hydraulic pump driven by a first electric motor and, using operating oil from a hydraulic pump driven by a second electric motor, to make the turning motor and the blade cylinder operate and to generate pilot pressures (see, e.g., Patent Document 1). This operation control device can suppress the rotational speed (number of rotations per unit time) of the second electric motor (electric motor for turning and so on) to be low when performing only travelling and the operation of the shovel device and suppress the rotational speed of the first electric motor (electric motor for travelling and so on) to be low when performing only turning and the operation of the blade, and thus energy consumption by the two electric motors can be suppressed. 
     Patent Document 1: Japanese Patent Publication No. 5096417 
     The hydraulic shovel comprises, in an operator cabin, operation levers such as travel operation levers with which to operate the traveling unit to travel and work operation levers with which to operate the turning body and the shovel device to work. The operation control device is configured to control the supply/discharge, supply directions, and flow rates of operating oil supplied from hydraulic pumps to hydraulic actuators according to the operation (operation directions and operation amounts) of the operation levers. In that case, making the working speeds of the hydraulic actuators (the working speeds corresponding to the operation amounts of the operation levers) adjustable may be required depending on the work content. For example, making the working speed of the hydraulic actuator corresponding to the operation of an operation lever slower than usual so that fine operation such as inching operation is made easier to perform or making the working speed faster than usual so as to raise the work speed (especially in the case of light load work) may be required. 
     SUMMARY OF THE INVENTION 
     In view of this problem, the present invention was made, and an object thereof is to provide an operation control device for a working vehicle which can variably adjust the working speed characteristic of the hydraulic actuator corresponding to the operation of an operation lever. 
     In order to achieve the above object, according to the present invention, an operation control device for a working vehicle (e.g., a hydraulic shovel  1  in the embodiment) which includes a hydraulic working device (e.g., a crawler mechanism  15 , turning body  20 , or shovel device  30  in the embodiment), comprises a hydraulic actuator (e.g., a traveling motor  16 L,  16 R, swing cylinder  34 , boom cylinder  36 , arm cylinder  37 , bucket cylinder  38 , blade cylinder  19 , or turning motor  26  in the embodiment) to drive the hydraulic working device; an operating oil supply source (e.g., a first hydraulic pump P 1  and first electric motor M 1 , or a turning hydraulic pump P 2  and second electric motor M 2  in the embodiment) that sends out operating oil necessary for driving the hydraulic actuator; an operating oil supply control device (e.g., a controller  150 , control valve unit  110 , and pilot pressure supply valve unit  130 , or a controller  150 , turn control valve  121 , and pilot pressure supply valve unit  130  in the embodiment) that performs control to supply operating oil sent out from the operating oil supply source to the hydraulic actuator; an operating device to be operated to make the hydraulic actuator work so as to drive the hydraulic working device and to output an operation output signal corresponding to this operation; and a working gain setting device (e.g., the controller  150  in the embodiment) that sets a gain of working speed of the hydraulic actuator corresponding to the operation of the operating device. The operation control device is configured such that the operating oil supply control device controls operating oil supply from the operating oil supply source to the hydraulic actuator based on the operation output signal from the operating device and the working speed gain set by the working gain setting device. 
     In the operation control device having the above configuration, the operating oil supply control device is preferably configured to control operating oil supply from the operating oil supply source to the hydraulic actuator such that the working speed of the hydraulic actuator is a gain corrected working speed obtained by coupling the working speed gain to a basic working speed of the hydraulic actuator obtained when controlling operating oil supply from the operating oil supply source to the hydraulic actuator based on the operation output signal. 
     In the operation control device having the above configuration, the operating oil supply control device may be configured to control operating oil supply from the operating oil supply source to the hydraulic actuator based on a corrected operation output signal obtained by multiplying the operation output signal by the working speed gain. 
     In the operation control device having the above configuration, the operating oil supply control device is preferably configured to comprise a flow rate control valve (e.g., control valves  111  to  118  in the embodiment) that performs switching supply/discharge to the hydraulic actuator of, switching a supply direction of, and flow rate control of operating oil sent out from the operating oil supply source, and, by controlling the opening degree of the flow rate control valve, to control operating oil supply from the operating oil supply source to the hydraulic actuator. 
     In the operation control device having the above configuration, the operating oil supply control device is preferably configured to comprise a valve working device (e.g., the pilot pressure supply valve unit  130  in the embodiment) that works to make the flow rate control valve work, and, by controlling operation of the valve working device, to control the opening degree of the control valve. 
     In the operation control device having the above configuration, the operating oil supply control device may be configured to comprise a switching control valve (e.g., the turn control valve  121  in the embodiment) that performs switching supply/discharge to the hydraulic actuator of and switching a supply direction of operating oil sent out from the operating oil supply source, and, by performing operation control of the switching control valve and controlling the amount of operating oil sent out from the operating oil supply source, to control operating oil supply from the operating oil supply source to the hydraulic actuator. 
     In the operation control device having the above configuration, the operating oil supply source is a hydraulic pump and an electric motor to drive the hydraulic pump. The operating oil supply control device is preferably configured to, by controlling the rotational frequency of the electric motor, control the amount of operating oil sent out from the hydraulic pump. In that case, the hydraulic pump is preferably a fixed-capacity-type hydraulic pump. 
     In the operation control device having the above configuration, the operating oil supply source may be a variable-capacity-type hydraulic pump and an engine to drive the hydraulic pump, and the operating oil supply control device may be configured to, by controlling the capacity of the variable-capacity-type hydraulic pump, control the amount of oil sent out from the hydraulic pump. 
     The operation control device having the above configuration, preferably comprises a working speed gain setting operating device (e.g., a working gain setting indicator  170  in the embodiment) that is operated to set the working speed gain and that outputs a signal for setting the working speed gain according to that operation to the working gain setting device. 
     With the operation control device for the working vehicle according to the present invention, the working speed gain is set by the working gain setting device, so that the working speed of the hydraulic actuator for the same operation amount of the operating device can be adjusted. For example, by setting the working speed gain to be smaller, the working speed of the hydraulic actuator for the same operation amount of the operating device can be made slower. Thus, delicate work in which the hydraulic actuator is made to operate at very slow speed can be precisely performed. Further, by setting the working speed gain to be larger, the working speed of the hydraulic actuator for the same operation amount can be made faster. Thus, the hydraulic actuator can be made to operate at high speed so as to improve work efficiency. 
     Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. 
    
    
     
       BRIEF DESCRIPTIONS OF THE DRAWINGS 
       The present invention will become more fully understood from the detailed description given herein below and the accompanying drawings which are given by way of illustration only and thus are not limitative of the present invention. 
         FIG.  1    is a perspective view of a hydraulic shovel comprising an operation control device according to the present invention. 
         FIG.  2    is a hydraulic circuit diagram showing the operation control device according to the present invention. 
         FIG.  3    is a hydraulic circuit diagram for explaining the control content when a controller in the operation control device performs operation control of an arm cylinder and a bucket cylinder. 
         FIG.  4    is a hydraulic circuit diagram for explaining the control content when the controller performs operation control of a turning motor. 
         FIG.  5    is a graph schematically showing the way that the correspondence relation between the operation amount of an operation lever and a supply flow rate changes based on a working speed gain. 
         FIG.  6    is a graph illustrating the correspondence relation between the signal level of an operation output signal and working speed. 
         FIG.  7    is a graph schematically showing the way that pilot pressure and the working speed of a working hydraulic actuator change based on the operation output signal and the working speed gain. 
         FIG.  8    is a graph schematically showing the way that the rotational frequency of a second electric motor and the working speed of a turning motor change based on the operation output signal and the working speed gain. 
         FIG.  9    is a graph illustrating the correspondence relation between a first operation output signal and necessary rotational frequency. 
         FIG.  10    is a graph illustrating the correspondence relation between a second operation output signal and necessary rotational frequency. 
         FIG.  11    is a diagram illustrating a configuration where a variable-capacity-type pump and an engine are used. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     An embodiment of the present invention will be described below with reference to the drawings. The present embodiment describes a crawler type of hydraulic shovel (excavator) as an example working vehicle comprising an operation control device according to the present invention. First, the entire configuration of the hydraulic shovel  1  will be described principally with reference to  FIG.  1   . 
     The hydraulic shovel  1  is configured to comprise a movable traveling unit  10 , a turning body  20  horizontally pivotally provided on the top of the traveling unit  10 , and a shovel device  30  provided on the front of the turning body  20  as shown in  FIG.  1   . The traveling unit  10 , the turning body  20 , and the shovel device  30  are driven by hydraulic actuators. 
     The traveling unit  10  comprises a pair of left and right crawler mechanisms  15  on both right and left sides of a traveling unit frame  11  which each have a drive wheel, a plurality of slave wheels, and a crawler belt  13  placed around these wheels. The left and right crawler mechanisms comprise left and right traveling motors  16 L,  16 R (hydraulic actuators) to rotationally drive the drive wheels. The traveling unit  10  can travel in any direction and at any speed by controlling the rotational direction and rotational speed of the right and left traveling motors  16 L,  16 R. A blade  18  is vertically swingably provided on the front of the traveling unit frame  11 . The blade  18  is vertically swingable by extending and contracting a blade cylinder  19  (a hydraulic actuator) provided across between the traveling unit frame  11  and the blade. 
     A turning mechanism is provided in the center of the top of the traveling unit frame  11 . This turning mechanism comprises an inner race fixed to the traveling unit frame  11 , an outer race fixed to the turning body  20 , a turning motor  26  (a hydraulic actuator, see  FIG.  2   ) provided in the turning body  20 , and a rotary center joint for supplying operating oil from a hydraulic pump provided in the turning body  20  to the right and left traveling motors  16 L,  16 R and blade cylinder  19  provided in the traveling unit  10 . The turning body  20  is horizontally pivotally attached via this turning mechanism to the traveling unit frame  11  and is turnable in right and left directions with respect to the traveling unit  10  by operating the turning motor  26  to rotate normally or reversely. A main-body-side bracket  22  protruding forward is provided on the front of the turning body  20 . 
     The shovel device  30  includes a boom bracket  39  attached to be swingable in right and left directions with a vertical axis as the center to the main-body-side bracket  22 , a boom  31  attached to be vertically swingable (up/down movable) via a first swing pin  35   a  to the boom bracket  39 , an arm  32  attached to be vertically swingable (bend/stretchable) via a second swing pin  35   b  to the tip of the boom  31 , and a link mechanism  33  provided on the tip of the arm  32 . The shovel device  30  further includes a swing cylinder  34  (a hydraulic actuator) provided across between the turning body  20  and the boom bracket  39 , a boom cylinder  36  (a hydraulic actuator) provided across between the boom bracket  39  and the boom  31 , an arm cylinder  37  (a hydraulic actuator) provided across between the boom  31  and the arm  32 , and a bucket cylinder  38  (a hydraulic actuator) provided across between the arm  32  and the link mechanism  33 . 
     The boom bracket  39  is swingable in right and left directions with respect to the turning body  20  (the main-body-side bracket  22 ) by operating the swing cylinder  34  to extend and contract. The boom  31  is swingable upward and downward (up/down movable) with respect to the main-body-side bracket  22  (the turning body  20 ) by operating the boom cylinder  36  to extend and contract. The arm  32  is swingable upward and downward (bend/stretchable) with respect to the boom  31  by operating the arm cylinder  37  to extend and contract. 
     Various attachments as hydraulic working devices such as a bucket, breaker, crusher, cutter, and auger device can be vertically swingably attached to the tip of the arm  32  and the link mechanism  33 . The attachment attached to the tip of the arm  32  is vertically swingable with respect to the arm  32  via the link mechanism  33  by operating the bucket cylinder  38  to extend and contract. First to third attachment connection ports  41  to  43  to which can be connected a hydraulic hose for supplying operating oil to the hydraulic actuator of these attachments are provided on both left and right side surfaces of the arm  32 . 
     The turning body  20  includes a turning frame  21  on the front of which the main-body-side bracket  22  is provided and an operator cabin  23  provided on the turning frame  21 . The operator cabin  23  forms an operator room in a substantially rectangular box shape in which an operator can get and is provided at the left side with a cabin door  24  which can be laterally opened and closed. Inside the operator cabin  23 , there are provided an operator seat on which the operator sits facing forward, a display device to display a variety of vehicle information of the hydraulic shovel  1 , and various operation switches to be operated by the operator. Further, inside the operator cabin  23 , there are provided an operating device  160  (see  FIG.  2   ) which is operated to operate hydraulic actuators and a working gain setting indicator  170  (see  FIG.  2   ) which is operated to set working speed gains of the hydraulic actuators. The operating device  160  has, as its operation portion to be operated by the operator, left and right travel operation levers or travel operation pedals (none are shown) with which to operate the traveling unit  10  to travel, left and right work operation levers  161 ,  162  (see  FIG.  3   ) with which to operate the turning body  20  and the shovel device  30  to work, and a blade operation lever (not shown) with which to operate the blade  18  to work. 
     In the hydraulic shovel  1 , an operator gets in the operator cabin  23  and inclines backward and forward in operation the left and right travel operation levers (or travel operation pedals), thereby making the left and right crawler mechanisms  15  (the left and right traveling motors  16 L,  16 R) drive according to the operation directions and operation amounts thereof, so that the hydraulic shovel  1  can be made to travel. Further, by inclining backward and forward, and right and left in operation the left and right work operation levers  161 ,  162 , the turning body  20  and the shovel device  30  are made to drive according to the operation directions and operation amounts thereof, so that work such as excavation can be performed. 
     A horn device  28  is provided on the front of the turning frame  21 . By pressing a horn switch in the operator cabin  23 , a warning tone to call attention can be emitted from the horn device  28  to the vicinity of the hydraulic shovel  1 . At the back of the turning frame body  20 , a mounting chamber, in which the main part of an operation control device  100  described later is mounted, is provided behind the operator cabin  23 . A counter weight  29  in a curved surface shape is provided to form the back wall of this mounting chamber. 
     The operation control device  100  comprises an operating oil tank T, a first hydraulic pump P 1  to discharge operating oil for making the left and right traveling motors  16 L,  16 R and the like operate, a turning hydraulic pump P 2  to discharge operating oil only for making the turning motor  26  operate, a control valve unit  110  to control the supply direction and flow rate of operating oil discharged from the first hydraulic pump P 1  and supplied to the left and right traveling motors  16 L,  16 R and the like, a turn control valve  121  to control the supply direction of operating oil discharged from the turning hydraulic pump P 2  and supplied to the turning motor  26 , and a pilot pressure supply valve unit  130  to generate and supply pilot pressures for controlling the operation of the control valve unit  110  and the turn control valve  121  respectively. 
     The control valve unit  110  comprises control valves to control the supply/discharge, supply directions, and flow rates of operating oil supplied to the left and right traveling motors  16 L,  16 R, the boom cylinder  36 , the arm cylinder  37 , the bucket cylinder  38 , the swing cylinder  34 , the blade cylinder  19 , and the first to third attachment connection ports  41  to  43  respectively. As these control valves, the unit  110  has left and right travel control valves  111 ,  112 , a boom control valve  113 , an arm control valve  114 , a bucket control valve  115 , a swing control valve  116 , a blade control valve  117 , and an attachment control valve  118 . In each of these control valves  111  to  118 , the incorporated spool is moved by a pilot pressure supplied from the pilot pressure supply valve unit  130 , and by the movement of the spool, the supply/discharge, supply direction, and flow rate of operating oil supplied to each hydraulic actuator can be controlled. 
     In the turn control valve  121 , as in the control valves  111  to  118 , the incorporated spool is moved by a pilot pressure supplied from the pilot pressure supply valve unit  130 . In the turn control valve  121 , by the movement of the spool, only the supply/discharge and supply direction of operating oil supplied to the turning motor  26  are controlled to switch. The flow rate control of operating oil supplied to the turning motor  26  (that is, the turn speed control of the turning body  20 ) is performed by the rotation control of a second electric motor M 2  described later. 
     The pilot pressure supply valve unit  130  is provided in a branch oil passage L 2  branching off from a pump oil passage L 1  leading from the discharge port of the first hydraulic pump P 1  to the control valve unit  110 . In the branch oil passage L 2 , a check valve  135  to keep oil pressure necessary for the pilot pressure supply valve unit  130  to generate pilot pressures is provided. With use of operating oil discharged from the first hydraulic pump P 1 , the pilot pressure supply valve unit  130  generates pilot pressures according to the respective operation directions and operation amounts of the travel operation levers (travel operation pedals), the work operation levers  161 ,  162 , and the blade operation lever provided in the operator cabin  23  and supplies to the corresponding control valves. The pilot pressure supply valve unit  130  has a plurality of electromagnetic proportional pilot pressure supply valves (described in detail later) for supplying the pilot pressures to the corresponding control valves. 
     The operation control device  100  further comprises a first electric motor M 1  to drive the first hydraulic pump P 1 , the second electric motor M 2  to drive the turning hydraulic pump P 2 , a battery  105  (a storage battery) rechargeable from an external power supply or the like, an inverter  106  that converts DC power from the battery  105  into AC power to change frequency and the magnitude of voltage, a first pressure sensor S 1  to detect the pressure (pump pressure) of operating oil discharged from the first hydraulic pump P 1 , a controller  150  to perform a variety of control (described in detail later), the above-mentioned operating device  160 , and the working gain setting indicator  170 . 
     The first and turning hydraulic pumps P 1 , P 2  are each a fixed-capacity-type hydraulic pump and discharge operating oil of flow rates according to the output of the first and second electric motors M 1 , M 2 . 
     Next, the contents of control by the controller  150  will be described.  FIG.  3    is a hydraulic circuit diagram for explaining the control content when the controller  150  performs operation control of the arm cylinder  37  and the bucket cylinder  38 .  FIG.  4    is a hydraulic circuit diagram for explaining the control content when the controller  150  performs operation control of the turning motor  26 . Components necessary for explaining the control content are extracted and shown in  FIGS.  3  and  4   . In the description below, the left and right traveling motors  16 L,  16 R, the boom cylinder  36 , the arm cylinder  37 , the bucket cylinder  38 , the swing cylinder  34 , and the blade cylinder  19 , of which the operation control is performed via the control valve unit  110 , are collectively called working hydraulic actuators. Although  FIG.  3    shows, as the control valve unit  110 , only the portion which performs the operation control of the arm cylinder  37  and the bucket cylinder  38 , the control valve unit  110  has control valves that perform the operation control of all the working hydraulic actuators. 
       FIGS.  3  and  4    show the left and right work operation levers  161 ,  162  as the operation portion of the operating device  160 . The work operation levers  161 ,  162  are joystick-type operation levers and output operation output signals corresponding to the operation thereof to the controller  150 . Specifically, the left work operation lever  161 , when operated backward and forward, outputs an operation output signal to make the arm cylinder  37  operate and, when operated rightward and leftward, outputs an operation output signal to make the turning motor  26  operate. In contrast, the right work operation lever  162 , when operated backward and forward, outputs an operation output signal to make the boom cylinder  36  operate and, when operated rightward and leftward, outputs an operation output signal to make the bucket cylinder  38  operate. The work operation levers  161 ,  162  are configured to output an operation output signal according to the operation amount (operation stroke) thereof, which signal becomes higher in signal level (e.g., in voltage value or current value) as the operation amount becomes larger. Likewise, the other operation levers (operation pedals) omitted from illustration in  FIGS.  3  and  4    output an operation output signal of a signal level according to the operation amount to make a corresponding hydraulic actuator operate to the controller  150 . Note that, in this example, each operation lever has the same configuration and that, when the operation amount of each operation lever is the same, the signal levels of the respective operation output signals are also the same. 
     The working gain setting indicator  170  has a hold operation portion  171  that the operator, holding with fingers, can rotate in operation within a predetermined angular range and is configured to output a working gain indicating signal corresponding to the operation amount (rotation angular position) of the hold operation portion  171  to the controller  150 . The working gain signal is an indicating signal to have the controller  150  set a working speed gain described later. The controller  150  sets the working speed gain according to this working speed gain signal (described in detail later). 
     The arm control valve  114  shown in  FIG.  3   , with the movement position of the incorporated spool being controlled by pilot pressures supplied from pilot pressure supply valves  131 ,  132  in the pilot pressure supply valve unit  130 , controls the supply direction and flow rate of operating oil supplied to the arm cylinder  37 . The pilot pressure supply valves  131 ,  132  are electromagnetic proportional pilot pressure control valves and are operated by pilot pressure control signals from the controller  150  to control the pilot pressures supplied to the arm control valve  114 . The pilot pressure from the pilot pressure supply valve  131  acts to move the spool of the arm control valve  114  leftward. The pilot pressure from the pilot pressure supply valve  132  acts to move the spool of the arm control valve  114  rightward. By controlling the pilot pressures from the pilot pressure supply valves  131 ,  132 , the movement direction and movement position (opening degree) of the spool of the arm control valve  114  are controlled. By this means, the supply/discharge, supply direction, and flow rate of operating oil supplied from the arm control valve  114  to the arm cylinder  37  can be controlled. In the pilot pressure supply valve unit  130 , pilot pressure supply valves to supply pilot pressures to the bucket control valve  115  and the other working hydraulic actuators are also provided. These pilot pressure supply valves are the same in configuration and action as the pilot pressure supply valves  131 ,  132 . 
     The turn control valve  121  shown in  FIG.  4   , with the movement position of the incorporated spool being switched between the middle position, right-side position, and left-side position by pilot pressures supplied from pilot pressure supply valves  133 ,  134  in the pilot pressure supply valve unit  130 , controls the supply direction of operating oil supplied to the turning motor  26 . The pilot pressure supply valves  133 ,  134  are operated by pilot pressure control signals from the controller  150  to switch between the state of supplying the pilot pressure to the turning motor  26  (called an on state) and the state of not supplying (called an off state). When the pilot pressure supply valve  133  is put in the on state to supply the pilot pressure, the spool of the turn control valve  121  moves leftward by this pilot pressure, so that the movement position of the spool is switched to the left-side position. When the pilot pressure supply valve  134  is put in the on state to supply the pilot pressure, the spool of the turn control valve  121  moves rightward by this pilot pressure, so that the movement position of the spool is switched to the right-side position. By controlling the operation of the pilot pressure supply valves  133 ,  134  in this way, the pilot pressures supplied to the turn control valve  121  are controlled. By this means, the movement position of the spool of the turn control valve  121  is switched, so that the supply/discharge and supply direction of operating oil supplied from the turn control valve  121  to the turning motor  26  are controlled. 
     The hold operation portion  171  of the working gain setting indicator  170  is rotated in operation by the operator, so that the controller  150  sets and adjusts the working speed gain. The working speed gain is set as a parameter (e.g., a coefficient) determining the correspondence relation between the operation amount of an operation lever in the operating device  160  and the working speed of the corresponding hydraulic actuator (the supply flow rate of operating oil supplied to the hydraulic actuator). By changing the setting of the working speed gain according to the rotation angular position of the hold operation portion  171 , the flow rate of supply to the hydraulic actuator (the working speed thereof) for the same operation amount can be adjusted. 
       FIG.  5    schematically represents the way that the correspondence relation between the operation amount of the operation portion and the amount of oil supplied to the actuator changes as the setting of the working speed gain becomes different. G L , G H , G M  shown in  FIG.  5    are respectively the minimum value, maximum value, and middle value of the working speed gain within the settable value range. The working speed gain can be set at any value greater than or equal to G L  and smaller than or equal to G H  according to the rotation angular position of the hold operation portion  171 . As shown in  FIG.  5   , by changing the working speed gain, the flow rate of supply to the hydraulic actuator (the working speed of the hydraulic actuator) for the same operation amount changes. Hence, adjustment can be made in which when the working speed of the hydraulic actuator for the same operation amount is desired to become faster, the working speed gain is set higher and in which conversely when desired to become slower, the working speed gain is set lower. Note that the specific value of the working speed gain is set as needed for each hydraulic actuator. For example, as to the working speed gain for the arm cylinder  37 , setting is made such that G L =0.8, G M =1.0, G H =1.2; as to the working speed gain for the bucket cylinder  38 , setting is made such that G L =0.5, G M =0.75, G H =1.0; and so on, as such, they can also be set at values different for each actuator. 
     The contents of the working speed control of hydraulic actuators by the controller  150  will be specifically described below. First, description will be made taking as an example the case where the arm cylinder  37  shown in  FIG.  3    is made to operate alone. Note that the rotation of the first electric motor M 1  is controlled according to the operation of the operation lever so as to control the flow rate of discharge from the first hydraulic pump P 1 , which will be described later. The controller  150  generates and outputs pilot pressure control signals based on the operation output signal from the left work operation lever  161  operated to make the arm cylinder  37  operate and the working gain indicating signal from the working gain setting indicator  170 . The pilot pressure supply valves  131 ,  132  adjust pilot pressures according to these pilot pressure control signals. As the method of generating pilot pressure control signals based on the operation output signal and the working gain indicating signal in this case, the following two methods will be described with further reference to  FIGS.  6  and  7   . 
     &lt;Method X1&gt; 
     In the first method X1, the controller  150  detects the operation output signal from the operating device  160  (here the work operation lever  161 ) and obtains the working speed A 1  (called a basic working speed) of a hydraulic actuator (here the arm cylinder  37 ) corresponding to the signal level (denoted as, e.g., K 1 ) of the detected operation output signal. Specifically, for example, as shown in  FIG.  6   , the correspondence relation between the signal level of the operation output signal and the working speed when the working gain indicating signal from the working gain setting indicator  170  is not taken into account (e.g., in the case of the working speed gain=1.0) is obtained beforehand by simulation or the like based on design values, and the working speed A 1  is obtained based on this correspondence relation. Although  FIG.  6    represents a linear correspondence relation as the correspondence relation between the operation output signal and the working speed, in reality, such a correspondence relation is set that a desired performance characteristic is obtained. This correspondence relation is often non-linear. 
     Next, the controller  150  sets the working speed gain G 1  corresponding to the detected working gain indicating signal. The working speed gain has a value corresponding to the rate at which to increase/decrease the working speed (the gain or attenuation rate) or the increase/decrease amount and is set according to the operation of the operator. For example, when the hold operation portion  171  of the working gain setting indicator  170  is operated to the leftmost rotation angular position within the rotation-allowable angle range thereof, the working speed gain is set at the smallest value G L  (e.g., 0.8). When the hold operation portion  171  is operated to the rightmost rotation angular position, the working speed gain is set at the largest value G H  (e.g., 1.2). G 1  is a working speed gain value satisfying G L ≤G 1 ≤G H . 
     After setting the working speed gain G 1 , the controller  150  couples the working speed gain G 1  to the working speed A 1  to obtain a gain corrected working speed A 2 . For example, the value of the working speed A 1  multiplied by the value of the working speed gain G 1  is taken as the value of the gain corrected working speed A 2  (see  FIG.  6   ). If the working speed gain G 1  is smaller than 1.0, the gain corrected working speed A 2  is a speed smaller (slower) than the working speed A 1  and, if the working speed gain G 1  is greater than 1.0, is a speed greater (faster) than the working speed A 1 . When the gain corrected working speed A 2  is determined, the necessary flow rate (necessary supply flow rate) for making it operate at the gain corrected working speed A 2  is determined from the characteristic of the hydraulic actuator (arm cylinder  37 ). When the necessary supply flow rate is determined, the valve opening degree for supplying at the necessary supply flow rate is determined from the characteristic of the control valve (here the control valve  114 ), and the pilot pressures for achieving that valve opening degree can be obtained. The controller  150  outputs pilot pressure control signals to the inverter  106  to supply the obtained pilot pressures to the control valve. 
     By these pilot pressure control signals, the operation of the pilot pressure supply valves  131 ,  132  is controlled, so that pilot pressures supplied from the pilot pressure supply valves  131 ,  132  to the arm control valve  114  are controlled. And the movement direction and movement position (opening degree) of the spool of the arm control valve  114  are controlled by these pilot pressures, and by this means, the flow rate of operating oil supplied from the arm control valve  114  to the arm cylinder  37  is controlled, so that the working speed of the arm cylinder  37  is controlled. That is, according to the method X1, the pilot pressures supplied to the control valve  114  are controlled based on the operation output signal from the left work operation lever  161  and the working gain indicating signal from the working gain setting indicator  170 , and by this control of the pilot pressures, the working speed of the arm cylinder  37  is controlled. Specifically, with the same operation amount, when the working speed gain value is greater than 1.0, the working speed is faster than when the working speed gain value is 1.0, and when the working speed gain value is smaller than 1.0, the working speed is slower than when the working speed gain value is 1.0. By making the working speed gain value larger, the working speed of the hydraulic actuator (arm cylinder  37 ) can be raised, and by making the working speed gain value smaller, the working speed can be lowered. Thus, the working speed of the hydraulic actuator for the same operation amount can be adjusted as needed according to the work content or so on to perform work. 
     &lt;Method X2&gt; 
     In the second method X2, the controller  150  detects the operation output signal from the operating device  160  (the work operation lever  161 ) and the working gain indicating signal from the working gain setting indicator  170 . Then the working speed gain G 1  (G L ≤G 1 ≤G H ) corresponding to the detected working gain indicating signal (the rotation angular position of the hold operation portion  171  of the working gain setting indicator  170 ) is set. 
     Then the controller  150  multiplies the detected operation output signal by the working speed gain G 1  to obtain a corrected operation output signal. For example, the operation output signal of a signal level K 1  is multiplied by the working speed gain G 1  to obtain a corrected operation output signal of a signal level K 2 . The controller  150  outputs a pilot pressure control signal corresponding to the obtained corrected operation output signal to a pilot pressure supply valve (a corresponding one of the pilot pressure supply valves  131 ,  132 ). 
     By this pilot pressure control signal, as in the method X1, the operation of the pilot pressure supply valves  131 ,  132  is controlled, so that the pilot pressures supplied from the pilot pressure supply valves  131 ,  132  to the control valve  114  are controlled. Then by these the pilot pressures, the movement direction and movement position (opening degree) of the spool of the arm control valve  114  are controlled, and by this means, the flow rate of operating oil supplied from the arm control valve  114  to the arm cylinder  37  is controlled, so that the working speed of the arm cylinder  37  is controlled. That is, also with the method X2, the pilot pressures supplied to the control valve  114  are controlled based on the operation output signal from the left work operation lever  161  and the working gain indicating signal from the working gain setting indicator  170 , and by this control of the pilot pressures, the working speed of the arm cylinder  37  is controlled. 
     Although the above description has been made taking as an example the case where the working speed of the arm cylinder  37  is controlled, also in the case where the working speed of another working hydraulic actuator is controlled, control that is the same in content as the above control is performed.  FIG.  7    schematically represents the way that the pilot pressure from a pilot pressure supply valve and the working speed of a working hydraulic actuator change based on the operation output signal (the operation amount of the operation lever or the like) and the working speed gain. As shown in  FIG.  7   , as the working speed gain becomes smaller, the ratio of change in the working speed (pilot pressure) of the working hydraulic actuator to change in the operation output signal (operation amount) becomes smaller. Hence, by setting the working speed gain to be smaller than, e.g., 1.0, the working speed of the working hydraulic actuator for the operation amount is made slower, and thus delicate work in which the working hydraulic actuator is made to operate at very slow speed can be precisely performed. 
     Next, the content of the working speed control in the case where the turning motor  26  shown in  FIG.  4    is made to operate will be described. The controller  150  generates and outputs a rotational frequency control signal based on the operation output signal from the left work operation lever  161  operated to make the turning motor  26  operate and the working gain indicating signal from the working gain setting indicator  170 . The second electric motor M 2  adjusts the rotational frequency according to this rotational frequency control signal. As the method of generating the rotational frequency control signal based on the operation output signal and the working gain indicating signal in this case, the following two methods will be described with further reference to  FIG.  8   . For simplicity of description,  FIG.  6   , which can be applied to the working speed control of the turning motor  26 , is referred to below. 
     &lt;Method Y1&gt; 
     In the first method Y1, when the operation lever (here the work operation lever  161 ) is operated, the controller  150  detects the operation output signal from the operating device  160  and outputs a pilot pressure control signal to a pilot pressure supply valve. By this pilot pressure control signal, the pilot pressure supply valve (a corresponding one of the pilot pressure supply valves  131 ,  132 ) is switched from the off state to the on state. Further, thereby the opening degree of the turn control valve  121  is switched to a fully-open state. The controller  150  obtains the working speed A 1  (corresponding to the basic working speed) of a hydraulic actuator (here the turning motor  26 ) corresponding to the signal level (denoted as, e.g., K 1 ) of the operation output signal from the operating device  160 . For example, as in the above method X1, the correspondence relation between the signal level of the operation output signal and the working speed when the working gain indicating signal from the working gain setting indicator  170  is not taken into account (e.g., in the case of the working speed gain=1.0) is obtained beforehand, and the working speed A 1  is obtained based on this correspondence relation (see  FIG.  6   ). 
     Next, the controller  150  detects the working gain indicating signal from the working gain setting indicator  170  and the working speed gain G 1  corresponding to the detected working gain indicating signal is set. After setting the working speed gain G 1 , the controller  150  couples the working speed gain G 1  to the working speed A 1  to obtain a gain corrected working speed A 2 . For example, as in the above method X1, the value of the working speed A 1  multiplied by the value of the working speed gain G 1  is taken as the value of the gain corrected working speed A 2  (see  FIG.  6   ). 
     When the gain corrected working speed A 2  is determined, the supply flow rate necessary for making it operate at the gain corrected working speed A 2  is determined from the characteristic of the hydraulic actuator (turning motor  26 ). When the necessary supply flow rate is determined, the rotational frequency of the second electric motor M 2  for supplying at the necessary supply flow rate can be obtained from the characteristics of the second electric motor M 2  and the second hydraulic pump P 2 . The controller  150  outputs the rotational frequency control signal to the inverter  106  for the second electric motor M 2  to operate at the obtained rotational frequency. 
     The inverter  106 , having received this rotational frequency control signal, controls the rotational frequency of the second electric motor M 2 , and by this rotational frequency control, the flow rate of discharge from the turning hydraulic pump P 2  is controlled. Where the rotational frequency control of the second electric motor M 2  is performed, one of the pilot pressure supply valves  133 ,  134  is put in the on state, so that a pilot pressure is supplied to the turn control valve  121 . By this means, the movement position of the spool of the turn control valve  121  is switched to the right-side position or the left-side position. Hence, the flow rate of operating oil supplied from the turn control valve  121  to the turning motor  26  is determined by the flow rate of discharge from the turning hydraulic pump P 2 , that is, the rotational frequency of the second electric motor M 2 . That is, according to the method Y1, the rotational frequency of the second electric motor M 2  is controlled based on the operation output signal from the work operation lever  161  and the working gain indicating signal from the working gain setting indicator  170 , and by this control of the rotational frequency of the second electric motor M 2 , the working speed of the turning motor  26  is controlled. Specifically, with the same operation amount, when the working speed gain value is greater than 1.0, the working speed is faster than when the working speed gain value is 1.0, and when the working speed gain value is smaller than 1.0, the working speed is slower than when the working speed gain value is 1.0. By making the working speed gain value larger, the working speed of the hydraulic actuator (turning motor  26 ) can be raised, and by making the working speed gain value smaller, the working speed can be lowered. Thus, the working speed of the hydraulic actuator for the same operation amount can be adjusted as needed according to the work content or so on to perform work. 
     &lt;Method Y2&gt; 
     In the second method Y2, when an operation lever (here the work operation lever  161 ) is operated, the controller  150  detects the operation output signal from the operating device  160  and outputs a pilot pressure control signal to a pilot pressure supply valve. By this pilot pressure control signal, the pilot pressure supply valve (a corresponding one of the pilot pressure supply valves  133 ,  134 ) is switched from the off state to the on state. Further, thereby the opening degree of the turn control valve  121  is switched to a fully-open state. The controller  150  detects the working gain indicating signal from the working gain setting indicator  170  and the working speed gain G 1  corresponding to the detected working gain indicating signal is set. 
     Next, the controller  150  multiplies the detected operation output signal by the working speed gain G 1  to obtain a corrected operation output signal. For example, the operation output signal of a signal level K 1  is multiplied by the working speed gain G 1  to obtain a corrected operation output signal of a signal level K 2 . The controller  150  outputs a rotational frequency control signal corresponding to the obtained corrected operation output signal to the inverter  106 . 
     The inverter  106 , having received this rotational frequency control signal, controls the rotational frequency of the second electric motor M 2 , and by this rotational frequency control, the flow rate of discharge from the turning hydraulic pump P 2  is controlled. As in the method Y1, where the rotational frequency control of the second electric motor M 2  is performed, one of the pilot pressure supply valves  133 ,  134  is put in the on state, so that a pilot pressure is supplied to the turn control valve  121 . By this means, the movement position of the spool of the turn control valve  121  is switched to the right-side position or the left-side position. Hence, the flow rate of operating oil supplied from the turn control valve  121  to the turning motor  26  is determined by the flow rate of discharge from the turning hydraulic pump P 2 , that is, the rotational frequency of the second electric motor M 2 . That is, also in the method Y2, the rotational frequency of the second electric motor M 2  is controlled based on the operation output signal from the work operation lever  161  and the working gain indicating signal from the working gain setting indicator  170 , and by this control of the rotational frequency of the second electric motor M 2 , the working speed of the turning motor  26  is controlled. 
       FIG.  8    schematically represents the way that the rotational frequency of the second electric motor M 2  and the working speed of the turning motor  26  change based on the operation output signal (the operation amount of the operation lever  161 ) and the working speed gain. As shown in  FIG.  8   , as the working speed gain becomes smaller, the ratio of change in the working speed (the rotational frequency of the second electric motor M 2 ) of the turning motor  26  to change in the operation output signal (operation amount) becomes smaller. Hence, by setting the working speed gain to be smaller than, e.g., 1.0, the working speed of the turning motor  26  for the operation amount is made slower, and thus delicate work in which the turning body  20  is made to turn at very slow speed can be precisely performed. 
     As such, the controller  150  is configured to be able to set together the working speed gains of the working hydraulic actuators and the turning motor  26  for the operation of the operation levers of the operating device  160  according to the rotation angular position of the hold operation portion  171  of the working gain setting indicator  170 . Thus, the operator, only by rotating in operation the hold operation portion  171  of the working gain setting indicator  170 , can easily set and adjust the working speed characteristics of the hydraulic actuators for the operation amounts of the operation levers at one time. 
     Next, the control of the flow rate of discharge from the first hydraulic pump P 1  shown in  FIG.  3    will be described with further reference to  FIGS.  9  and  10   . In general, by feedback control in which the flow rate of discharge from the hydraulic pump P 1  is determined based on the difference between operating oil pressure on the hydraulic pump P 1  side and operating oil pressure on the working hydraulic actuator side, the flow rate of discharge from the hydraulic pump P 1  is controlled. However, if the flow rate of discharge from the hydraulic pump P 1  is controlled by this feedback control, control responsivity is relatively slow. Thus, there is concern that during the control of the flow rate of discharge from the first hydraulic pump P 1 , in the situation where the differential pressure abruptly changes, a control delay occurs, so that hunting is likely to occur and that in the situation where the differential pressure changes only slightly, the responsivity is likely to be poor. Accordingly, in the operation control device  100 , the controller  150  controls the flow rate of discharge from the first hydraulic pump P 1  as follows. 
     If the arm cylinder  37  is made to operate alone, the controller  150  controls the rotational frequency of the first electric motor M 1  according to the signal level (the operation amount of the work operation lever  161 ) of the operation output signal (called a first operation output signal) from the left work operation lever  161  operated to make the arm cylinder  37  operate. Specifically, the controller  150  controls the rotational frequency of the first electric motor M 1  such that as the signal level (the operation amount of the work operation lever  161 ) of the first operation output signal becomes larger, the flow rate of discharge from the first hydraulic pump P 1  increases and that a flow of the discharge flow rate necessary for making the arm cylinder  37  operate at a working speed corresponding to the signal level of the first operation output signal is discharged from the first hydraulic pump P 1 . For example, as shown in  FIG.  9   , the correspondence relation between the signal level of the first operation output signal and the rotational frequency of the first electric motor M 1  for obtaining the necessary discharge flow rate is obtained beforehand by simulation or the like based on design values, and the rotational frequency (called a necessary rotational frequency) of the first electric motor M 1  is obtained based on this correspondence relation. Then a rotational frequency control signal is outputted to the inverter  106  to achieve the obtained necessary rotational frequency so as to control the rotational frequency of the first electric motor M 1 . The first electric motor M 1  rotates at the necessary rotational frequency, so that a flow of the necessary discharge flow rate for making the arm cylinder  37  operate is discharged from the first hydraulic pump P 1 . In this case, operating oil discharged from the first hydraulic pump P 1  is supplied to the arm cylinder  37  via the control valve  114 . An opening characteristic such as the opening area corresponding to the valve opening degree is set beforehand such that, by its opening degree being controlled according to the operation amount of the work operation lever  161 , the control valve  114  can supply to the arm cylinder  37  at the necessary supply flow rate for making the arm cylinder  37  operate at the working speed corresponding to the operation amount. The necessary discharge flow rate of the flow discharged from the first hydraulic pump P 1  is set to be larger than the necessary supply flow rate of the flow supplied from the control valve  114  to the arm cylinder  37  (such that oil pressure on the inflow side of the control valve  114  is higher than that on the outflow side). 
     If the bucket cylinder  38  is made to operate alone, the controller  150  controls the rotational frequency of the first electric motor M 1  according to the signal level (operation amount) of the operation output signal (called a second operation output signal) from the right work operation lever  162 . Specifically, the controller  150  controls the rotational frequency of the first electric motor M 1  such that as the signal level (the operation amount of the work operation lever  162 ) of the second operation output signal becomes larger, the flow rate of discharge from the first hydraulic pump P 1  increases and that a flow of the discharge flow rate necessary for making the bucket cylinder  38  operate at a working speed corresponding to the signal level of the second operation output signal is discharged from the first hydraulic pump P 1 . For example, as shown in  FIG.  10   , the correspondence relation between the signal level of the second operation output signal and the rotational frequency of the first electric motor M 1  for obtaining the necessary discharge flow rate is obtained beforehand, and the necessary rotational frequency of the first electric motor M 1  is obtained based on this correspondence relation. Then a rotational frequency control signal is outputted to the inverter  106  to achieve the obtained necessary rotational frequency so as to control the rotational frequency of the first electric motor M 1 . The first electric motor M 1  rotates at the necessary rotational frequency, so that a flow of the necessary discharge flow rate for making the bucket cylinder  38  operate is discharged from the first hydraulic pump P 1 . In this case, operating oil discharged from the first hydraulic pump P 1  is supplied to the bucket cylinder  38  via the control valve  115 . An opening characteristic such as the opening area corresponding to the valve opening degree is set beforehand such that, by its opening degree being controlled according to the operation amount of the work operation lever  162 , the control valve  115  can supply to the bucket cylinder  38  at the necessary supply flow rate for making the bucket cylinder  38  operate at the working speed corresponding to the operation amount. The necessary discharge flow rate of the flow discharged from the first hydraulic pump P 1  is set to be larger than the necessary supply flow rate of the flow supplied from the control valve  115  to the bucket cylinder  38  (such that oil pressure on the inflow side of the control valve  115  is higher than that on the outflow side). 
     Although  FIGS.  9  and  10    represent a linear correspondence relation as the correspondence relation between the signal level of the operation output signal and the necessary rotational frequency, in reality, such a correspondence relation is set that a desired performance characteristic is obtained. This correspondence relation is often non-linear. The necessary discharge flow rate (necessary rotational frequency) for the signal level of the operation output signal (the operation amount of the work operation lever) is called a necessary discharge flow rate-operation amount ratio. This necessary discharge flow rate-operation amount ratio is determined by characteristics of the hydraulic actuator made to operate, the control valve supplying operating oil to that hydraulic actuator, and the like. Thus, the necessary discharge flow rate-operation amount ratio is often different for each hydraulic actuator. For example, as to the arm cylinder  37  and the bucket cylinder  38 , the necessary discharge flow rate-operation amount ratio (denoted as H 1 ) for the arm cylinder  37  is larger than the necessary discharge flow rate-operation amount ratio (denoted as H 2 ) for the bucket cylinder  38 . The correspondence relations shown in  FIGS.  9  and  10    are set based on the respective necessary discharge flow rate-operation amount ratios. Note that when the working speed gain is adjusted and changed, the necessary discharge flow rate-operation amount ratio also changes according to change in the working speed gain. 
     If the arm cylinder  37  and the bucket cylinder  38  are made to operate at the same time, the controller  150  obtains the necessary rotational frequency of the first electric motor M 1  corresponding to the signal level of the first operation output signal from the work operation lever  161  and the necessary rotational frequency of the first electric motor M 1  corresponding to the signal level of the second operation output signal from the work operation lever  162  and adds them. Then the controller  150  outputs a rotational frequency control signal to control the rotational frequency of the first electric motor M 1  to be the added necessary rotational frequency (called a sum necessary rotational frequency) to the inverter  106  so as to control the rotational frequency. For example, when the signal level of the first operation output signal is K A1 , and the signal level of the second operation output signal is K B1 , the necessary rotational frequency R A1  for when the signal level is K A1  and the necessary rotational frequency R B1  for when the signal level is K B1  are added to obtain the sum necessary rotational frequency (see  FIGS.  9  and  10   ). Note that the sum necessary rotational frequency corresponds to the value obtained by multiplying the signal level K A1  of the first operation output signal and the signal level K B1  of the second operation output signal respectively by ratios H 1  and H 2  as weight coefficients and adding the values after the multiplication. By the first electric motor M 1  rotating at the sum necessary rotational frequency, a flow of the necessary discharge flow rate for making the arm cylinder  37  and the bucket cylinder  38  operate at the same time is discharged from the first hydraulic pump P 1 . In this case, operating oil discharged from the first hydraulic pump P 1  divides into for the arm cylinder  37  and for the bucket cylinder  38  to be supplied. At this time, the division ratio corresponds to the ratio of the necessary supply flow rate of the flow supplied from the control valve  114  to the arm cylinder  37  according to the operation amount of the work operation lever  161  to the necessary supply flow rate of the flow supplied from the control valve  115  to the bucket cylinder  38  according to the operation amount of the work operation lever  162 . As to the control valves  114 ,  115 , their respective opening characteristics are set beforehand such that, by their opening degrees being controlled according to the operation amounts of the work operation levers  161 ,  162 , the division ratio corresponding to the ratio of the necessary supply flow rate for the arm cylinder  37  to the necessary supply flow rate for the bucket cylinder  38  is obtained. The necessary discharge flow rate of the flow discharged from the first hydraulic pump P 1  is set to be larger than the sum of the necessary supply flow rate of the flow supplied from the control valve  114  to the arm cylinder  37  and the necessary supply flow rate of the flow supplied from the control valve  115  to the bucket cylinder  38 . 
     Note that, if the arm cylinder  37  and the bucket cylinder  38  are made to operate at the same time, the controller  150  may add the signal level of the first operation output signal from the work operation lever  161  and the signal level of the second operation output signal from the right work operation lever  162  operated for making the bucket cylinder  38  operate. Then according to the added signal level (call a sum signal level), the controller  150  may control the rotational frequency of the first electric motor M 1  such that as the sum signal level (the operation amount of the work operation lever  161  and the operation amount of the work operation lever  162 ) becomes larger, the flow rate of discharge from the first hydraulic pump P 1  increases and that a flow of the necessary flow rate (necessary discharge flow rate) corresponding to the sum signal level is discharged from the first hydraulic pump P 1 . 
     Where the sum signal level is obtained, instead of simply adding the signal level of the first operation output signal and the signal level of the second operation output signal, the signal level of each operation output signal is preferably weighted according to the ratio between the necessary discharge flow rates (corresponding to the ratio of H 1  to H 2  between the necessary discharge flow rate-operation amount ratios) for the same signal level (operation amount) to be added. For example, if the arm cylinder  37  needs a larger discharge flow rate during operation than the bucket cylinder  38  even with the same signal level (operation amount), according to the ratio (e.g., 1.5:1.0) between the necessary discharge flow rates (e.g., the necessary discharge flow rates when the signal level (operation amount) is maximal), the signal level of the first operation output signal is multiplied by 1.5, and the signal level of the second operation output signal is multiplied by 1.0, and the signal levels after the multiplication are added to obtain a sum signal level. Then the necessary discharge flow rate (necessary rotational frequency) corresponding to the obtained sum signal level is obtained. Specifically, the obtained sum signal level is the signal level obtained by converting the signal level of the first operation output signal into a signal level of the second operation output signal and adding them, and hence by multiplying the sum signal level by the necessary discharge flow rate-operation amount ratio H 2  corresponding to the bucket cylinder  38 , the necessary discharge flow rate (necessary rotational frequency) can be obtained. 
     Although description has been made taking as an example the case where the arm cylinder  37  and the bucket cylinder  38  are made to operate at the same time, also when a plurality of (may be three or more) other working hydraulic actuators are made to operate at the same time, the same control is performed. As such, the configuration is made such that the rotational frequency of the first electric motor M 1  is controlled according to the operation amount of the operation lever or the like and that thereby the flow rate of discharge from the first hydraulic pump P 1  is controlled, so that a necessary amount of oil can be precisely supplied. Further, in the situation where a small flow rate of discharge from the first hydraulic pump P 1  suffices, the rotational frequency of the first electric motor M 1  can be made smaller, so that power consumption can be suppressed. Yet further, since the fixed-capacity-type first hydraulic pump P 1  is used, cost can be suppressed and ease of maintenance is improved as compared with the use of a variable-capacity-type hydraulic pump. As opposed to the case of performing feedback control in which the flow rate of discharge from the hydraulic pump P 1  is determined based on the difference between operating oil pressure on the first hydraulic pump P 1  side and operating oil pressure on the working hydraulic actuator side, in control of the discharge flow rate, hunting is not likely to occur, nor is the responsivity likely to poor. 
     Although in the above description the first hydraulic pump P 1  is a fixed-capacity-type hydraulic pump, a variable-capacity-type hydraulic pump may be used. In the case of using a variable-capacity-type hydraulic pump, the discharge flow rate control may be performed by controlling the capacity of the hydraulic pump. Further, in that case, the variable-capacity-type hydraulic pump may be driven by not an electric motor but an engine.  FIG.  11    illustrates a variable-capacity-type hydraulic pump P 3  driven by an engine E 1 . The capacity of the variable-capacity-type hydraulic pump P 3  is controlled by a capacity control device  180  having, e.g., a piston  181  driven hydraulically or electromagnetically. With this configuration, the controller  150  has the capacity control device  180  operate to control the capacity of the variable-capacity-type hydraulic pump P 3  according to a sum signal level obtained by adding the signal levels of the operation output signals from the operating device  160  such that as the sum signal level becomes larger, the flow rate of discharge from the variable-capacity-type hydraulic pump P 3  increases. Further, a variable-capacity-type hydraulic pump may be used instead of the turning hydraulic pump P 2 , and the discharge flow rate control thereof may be performed by controlling the capacity of the hydraulic pump. In that case, the variable-capacity-type hydraulic pump may be driven by not an electric motor but an engine. 
     Although the embodiment of the present invention has been described above, the scope of the present invention is not limited to the above embodiment. For example, although the above embodiment describes the configuration where the opening degrees of the control valves  111  to  118  are controlled by pilot pressures supplied from the pilot pressure supply valve unit  130 , a configuration may be made where, with electromagnetic proportional control valves as the control valves  111  to  118 , the opening degrees of the control valves  111  to  118  are controlled electromagnetically. Or the opening degrees of the control valves  111  to  118  may be controlled using a drive device such as an electric motor. Although the above embodiment describes the configuration where pilot pressures are generated using operating oil from the first hydraulic pump P 1 , a configuration may be made where a for-pilot hydraulic pump, driven together with the first hydraulic pump P 1  by the first electric motor M 1 , is provided and where pilot pressures are generated using operating oil from this for-pilot hydraulic pump. 
     A configuration may be made where the setting (initial setting) of an operating characteristic of the hydraulic actuator for the operation of an operation lever can be changed for each hydraulic actuator. For example, in order to change the setting of the correspondence relation between the operation amount of an operation lever and the working speed (the amount of supplied oil) of the corresponding hydraulic actuator, a configuration may be made where the setting of the necessary discharge flow rate-operation amount ratio can be changed or where the setting of the working speed gain value can be changed. A configuration can be made where this setting change is performed via, e.g., a portable computer (having a program to change the setting incorporated therein) or the like electrically connected to the controller  150 . 
     Further, a configuration may be made where, when the crawler mechanisms  15  or the shovel device  30  are made to operate at the same time as the turning operation of the turning body  20 , control is performed to decrease the discharge flow rate of the first hydraulic pump P 1  by the magnitude of the discharge flow rate of the turning hydraulic pump P 2  (to decrease the horsepower of the first hydraulic pump P 1  by the magnitude of the horsepower of the turning hydraulic pump P 2 ). Although the above embodiment illustrates an example where the present invention is applied to the hydraulic shovel, the present invention can be applied to working vehicles other than hydraulic shovels likewise to obtain the same effect. 
     The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims. 
     RELATED APPLICATIONS 
     This invention claims the benefit of Japanese Patent Application No. 2019-072590 which is hereby incorporated by reference.